A Hybrid Owner’s winter survival guide

Discussion in 'Articles' started by msantos, Nov 20, 2008.

  1. msantos

    msantos Eco Accelerometrist

    A Hybrid Owner’s winter survival guide

    Manuel Santos - CleanMPG - November 19, 2008

    Preparing your Civic Hybrid and Toyota Prius for winter driving

    As with most things in life, a bit of upfront diligence and preparation can do wonders later on. And on this note, nothing is more true than preparing your hybrid vehicle for the challenges of winter. For those of us who have extended periods of snow and ICE during the winter season, any preparation should extend well beyond one’s driving habits and behaviors.

    W A R N I N G
    The information contained in this article is intended to mitigate the effects of winter driving particularly in sub-freezing temperatures. Using some of the recommendations under any other circumstances is not recommended and can even be dangerous. Please exercise caution and only proceed if you understand the goals and principles of these recommendations.

    Front Intake (grille) blocking

    Blocking the front intake grille on a hybrid vehicle is one of the most significant improvements that any hybrid owner can make to offset the inevitable loss in fuel economy during the winter months.

    Why block the front grille?

    On the Prius and Civic Hybrid the optimal performance range occurs when the gas engine temperature is between 60C and 90C. In between those ranges both cars offer additional stages of operation particularly in areas affecting electric propulsion, regeneration and fuel consumption rates. However, when the ambient temperatures fall below freezing , it not only takes longer for the vehicle’s engine to arrive to the optimal range, but sometimes depending on how low the ambient temperature actually is, it may not even reach ideal operation at all.
    The main reason why this is so is because as the vehicle moves forward the colder air rushes into the engine bay and prevents the engine from warming up as quickly as it should.

    Now, if we factor in the fact that the car is being operated by a human being, the climate control is also likely to be set to "warm up" the passenger cabin. This too helps deplete/steal the heat the engine is producing thus slowing down the warm-up process even further.

    Because the Prius and HCH have smaller engines, they also produce less heat since heat produced is a function of how little fuel gets burnt per unit of time. This makes these and other small cars more sensitive to cold weather operation and causes severe losses of fuel economy performance.

    How to block the front grille?

    Blocking of the front grille must be done safely and correctly. This can be performed with an after market kit or easily improvised in a matter of 30 minutes or less depending on the availability of materials.

    The preferred method of blocking the front grille on the HCH and Prius is to install properly sized segments of ¾ inch pipe insulation in the front grille openings. This pipe insulation can be bought at most hardware stores and is usually found nearby the copper tubing (plumbing section). A maximum of two segments is sufficient to perform the blocking on either car.

    Winter Blocking the 2010 3G Prius: Top blocking may require some creative cutting of the foam to ensure a secure and thorough fit. Bottom blocking only requires small vertical cuts on the foam to make it past the vertical fins and allow for a flush and secure fit.

    Winter Blocking the 2006-2008 2G HCH: Top blocking requires proper sizing and one vertical cut on the foam to ensure a secure and flush fit. Bottom blocking only requires small cuts on the foam to make it past the vertical fins and allow for a flush and secure fit.
    2009-2010 HCH units: Require the use of a flattened out foam tube that is then cut to match the openings and then tied against the grille with nylon tie wraps.

    First, identify how much of the grille to want to block. If you live in a particularly cold area you may wish to plan for full coverage of the front grille. Again, the blocking must match the conditions.

    Second, purchase the foam pipe insulation segments you need and cut the appropriate segments. These segments may need to be notched with a sharp utility knife or scissors so that they can be properly inserted into the openings without bending over the grille cross members. This notching will make the segments look straight without making the grille blocking effort look bad or loose.

    How much blocking do we apply?

    Generally we want to be very careful when operating the vehicle above freezing temperatures especially if the grille is fully blocked. The optimal temperature ranges on the Prius and HCH-2 do not exceed 90C (194F) . Anything above 90C and the vehicles radiator fan will run, so it is in our interest to ensure that we gradually or completely remove the blocking if the ambient temperatures are too high. Failure to remove the blocking in warmer days will likely cause the engine to overheat and fail in addition to forcing greater energy consumption resulting from the operation of the radiator fan.

    A very useful tool to monitor the actual engine temperatures is to use a ScanGauge device. It not only displays the engine coolant temperatures but also the intake temperatures which can help us determine the proper amount of grille blocking to perform. Of course, a ScanGauge has many other uses but in this particular scenario it is the best tool any Prius or HCH owner can use.

    Here is some grille blocking guideline based on actual experiences in a 2007 Prius and 2007 HCH over a 15-20 minute commute:

    Front Grille blocking as a function of ambient temperature

    The table above was derived from average temperatures observed in both vehicles during the period of January 2007 to May 2007. The temperatures were recorded daily at the end of every commute as indicated by the ScanGauge II (version 3.0).

    The above table values were matched to these engine temperatures

    The Engine Block Heater

    Most engine block heaters consist of a small “plug-like” heating element that is bolted into a specially designed port on the engine block. This diminutive heating element is as simple as it is effective and will heat up the engine coolant which in turn keeps the entire engine block at a temperature higher than the ambient temperature. Most engine block heaters provide a power rating of approximately 400 watts when operated at a household voltage of 110V.


    Prius and HCH-2 Block heater

    Plugging in the block heater when the vehicle is parked will enable the engine to arrive to its optimal operational temperature sooner thereby benefiting fuel economy and lowering vehicle emissions. Of course, in colder climates the use of an engine block heater has many other benefits including reducing wear and tear on the engine components and reducing the need to perform warm-up idling among others.

    Testing your Engine Block Heater

    [xfloat=right]http://www.cleanmpg.com/photos/data/506/TestingBlockHeater.jpg[/xfloat]How do we know the engine block heater is working? Why would you want to know?
    With time the Ebh plug or its cord will develop a defect due to fatigue or simply because we tried to drive off while forgetting it was plugged in (I am guilty of this too).
    You may choose an auditory test or a test with a digital multi-meter. An auditory test is possible in the first 20 seconds after plugging in the Ebh cord to a live outlet. You should hear a faint crackling noise during the initial warm-up which is a clear indicator that the Ebh is working.

    When using a digital multi-meter set the device to measure resistance (ohms) and you should read 33-36 ohms when measuring the resistance across the two flat poles at the end of the Ebh plug (don't do this with the car plugged in). If you do not read any resistance then the cord or plug may have developed a problem and may need to be repaired or replaced.

    When to use a block heater, and how long to leave it on

    [xfloat=left]http://www.cleanmpg.com/forums/../photos/data/506/IntermaticWallMountedTimers.jpg[/xfloat]A block heater should be powered on long enough to make a measurable difference in how quickly a vehicle’s engine warms up. When already underway, the quicker the engine warms up, the sooner it will enter its efficient operating stages.
    In the winter time the block heater may have to be "on" over a longer period of time, perhaps 6-8 hours or more in extreme cold temperatures. In the warmer months it needs much less "plug-in" time. For instance, for those that want the ultimate benefits of a block heater in the summer months, a 1-2 hour plug-in time should be adequate. Typically, block heaters can raise the temperature of the engine block by approximately 30C-40C above the ambient temps.

    Leaving the block heater on for too short a period will help but will not materialize the fuel economy gains it is capable of. Conversely, leaving the block heater on for too long will amount to diminished benefits since much of the heat will be lost into the surrounding air while parked.

    For this reason, it is usually a good idea to plug the block heater to a timer device that will control when and how long the block heater will stay on for. These timers should be able to handle 1000 Watts of power and they usually come in many forms and features. A home improvement store or Walmart will carry these which range in price from $30 to all the way up to $120 for the fancier models.

    An example of two wall mounted Digital timers from Intermatic. Each timer controls a different car and each can have up to 7 distinct power ON, Power OFF programs for weekdays and weekends. Retails for roughly $30 each and saves roughly as much over a few years of operation.

    The Tires

    Even in winter, keeping the tires pressures up is very important for great FE (fuel economy). Why? Because in colder temperatures the internal air pressure effect on the tire is reduced thus causing them to run flatter. Since a flatter running tire induces more friction on the road surface, we certainly do not want to neglect the air pressure in the colder days either.

    So what is the best approach for maintaining the proper air pressure? Basically two approaches:
    1. Regular use a good digital tire pressure gauge. Ideally check the tire pressures every 1 or 2 weeks.
    2. Install and use a direct type Tpms system.
    Now that we have a monitoring regime in place let us focus on the ideal tire pressures. The main determinant for setting the proper tire pressure is the tire’s own maximum pressure rating. This rating is present on the sidewall of every tire and should be used as the authoritative reference marker. The recommended tire pressure usually present in the vehicle’s door jamb and owner’s manual are not intended to favor fuel efficiency and tire durability. Instead these recommended values favor ride comfort which is critical element of a vehicles show-room and test drive appeal.

    So, assuming that we identify the maximum tire pressure rating for the tires, we then establish a baseline setting for our vehicles that takes into account our FE goals and comfort aspirations. For instance, if the maximum sidewall pressure rating is 44 PSI then we may pick a pressure baseline from the following table.

    Recommended scenario for winter tires with a maximum sidewall pressure rating of 44 psi

    In many cases, it is quite possible to run the tires at a much higher pressure than the indicated maximum rating. However, care should be exercised in ensuring that the tires are not only free of defects (due to punctures and age) but that they are also used in a proper and controlled setting.
    According to many studies the rolling resistance continues to decrease even as the tire pressure is raised beyond its maximum rating, albeit at an ever diminishing amount to such an extent that the FE benefits may no longer make up for the lower peace of mind. In any case, and whatever pressure setting you choose please exercise caution when raising your tire pressures beyond the stated maximum rating in the winter months as the frozen tire structure is far less resilient.

    Selecting the proper winter tire

    If you have snow and ICE on the ground you SHOULD NOT rely on the OEM LRR tires to carry you and your loved ones your through the winter months. Even though the OEM tires offer unrivaled fuel economy in the summer months, they also are the absolute worst for operation in adverse weather conditions.

    For your sake and that of others sharing the roads with you, make sure you swap those tires with good winter grade rubber. Ideally, you should have a set of cheaper rims (steel) where the winter tires are mounted; and when the warm weather returns you simply swap the winter wheels with the OEM set that came with your car.

    Why a different set of rims for your winter tires? Because the OEM aluminum rims will get damaged by the winter time salt and sand that is spread on our roads. Such abuse is often noticeable after the first winter and does nothing to enhance the value of your vehicle as it ages. There's also the aspect of convenience since all we need to do is to switch the wheels twice a year which is often better, simpler and quicker.

    Last thought on winter driving tires

    Q: Isn't it possible that the "very best" all-season tire can be better than the worst and cheapest winter tire in matters of safety and handling ?

    A: Definitely not ! In fact, several regions in North America have made it illegal to operate a motor vehicle without appropriate winter tires.

    And here's a site containing a set of videos that will expose the inadequacies of all season tires in winter driving:

    Be Tire Smart (Full tests of Winter tires v.s. All-Season) - MUST SEE

    Tire Rack Tire Test - Winter/Snow vs. All-Season vs. Summer Tires on Ice

    Recommended Winter tires

    Michelin X-ICE – These offer good wear, class leading safety with effective adhesion and minimal impact on fuel economy which is a VERY tall order from any other winter tire brand. This brand/model is absolutely recommended for both HCH and Prius vehicles if you value safety, enhanced fuel economy performance and low noise levels.

    Please note that most snow/ICE tires are directional in that they can only be driven in one direction. This means that they can not be rotated as easily and in the same pattern as the OEM tires. To do so will compromise the handling and safety of the vehicle in adverse conditions.
    Look for any embossed arrows in the tire sidewall to indicate if your winter tires are directional. When in doubt, call your dealer or tire shop to make sure.

    The Engine/Intake Air Filter

    During the winter months the engine air filter gets very dirty on the account of extra pollutants present in the air. These pollutants consist of various substances that range from road salt to silicates and other chemicals produced through the exhaust of other vehicles. Many of these substances are present in higher numbers in the air for many reasons and they are often quite hard to avoid. By having a clean air filter we are ensuring that not only the engine breathes more freely but also that we protect many downstream components such as:
    • Valves and cylinder seals
    • O2 Sensors
    • EGR valves
    • Catalytic converter
    • Exhaust system

    Can you guess which is the "dirty 1 year old" filter with just 10K miles ?

    The most noticeable side effect that a cleaner engine can have on the performance of an engine during the winter months is the increase fuel economy performance. Not only because the entire combustion control system can more accurately administer the fuel to match the volume of air but also because the oil will breakdown far more slowly due to less foreign substances and hence promote reduced engine friction.

    Basic maintenance rules call for a yearly inspection of the air filters and a sooner replacement than the manufacturer recommended interval if the filter shows the presence of dirt.

    Oil and viscosity ratings

    This is without as doubt, a top perennial issue regardless of season and temperature. A higher quality low viscosity (the lowest your vehicle can accommodate) is always preferable and is no less important in the colder winter months. For your HCH , make sure you are using Honda’s 0W20 or other similarly rated synthetic. Using any other oil rating on the HCH will lead to extremely poor fuel efficiency and faster engine wear.

    [​IMG] [​IMG]
    Honda oil used on my HCH-2's and the Mobil 1 0W20 used by dealer on my Prii

    On the Prius, consider using a synthetic oil and if you feel adventurous you may contemplate using a 0W20 as well – I did so with the cooperation of my dealership and so far the results are very good. I have been using 0W20 oil on my company Prius vehicles without any ill effects but some dealers will not agree to the substitution. Nevertheless, check with your dealer first as from a warranty fulfillment perspective it is better to be safer than sorry.

    Windshield washer fluid

    This seemingly trivial fluid can at times become a head ache for many drivers especially if the fluid is heavily diluted in water. When driving though colder weather it is important not to ignore the freeze resistance rating of the fluid. Blocking the front grille can also have a positive influence on the temperature of the windshield fluid as it enables the engine cavity to retain more of the heat produced by the gas engine while in operation.

    Typical winter rated windshield washer fluid

    Windshield washer fluid can come in a variety of colors (blue, green, yellow, pink, etc) but the most important attribute of suitability is that anti-freeze rating. The rest is a matter of brand, cost and color.

    Don't forget to inspect the windshield washer tubing for leaks as the alcohol contained in the fluid can compromise the integrity of hoses and wiring and connectors in the engine bay. Just to make sure, test your nozzles regularly especially after a good wax job since excess wax or paint sealant may build up and clog the spray/squirt nozzles.

    Re-fueling your vehicle

    There aren’t many things we can do when it comes to winter gas formulations. Even those of us who live in the warmer states/provinces end up having no choice when it comes to consuming this type of winter gas. Despite the benefits that these gas formulations offers the average driver, a loss in energy density in unavoidable and always contributes to lower fuel economy.
    Despite this, we can still minimize the impact of these winter formulations by following most of the sensible care and maintenance advice and also by selecting fuel brands of higher quality – which are commonly – referred as Tier 1 brands. As usual, the Shell brand does appear to offer some consistency in the quality of their gas in the summer months which not surprisingly also extends to the winter months as many of us can attest.

    Washing your car in the winter

    No. This is not a joke. Maintaining your car clean in the winter not only will allow it to look good but will also allow it to travel lighter and more efficiently. Focusing on the wheel wells, fenders and under-body is quite helpful as those areas can carry a pretty hefty load of ICE and snow. A study performed several years ago found that an average vehicle can carry as much as 60 lbs (or more) worth of packed ICE and snow for several weeks with a significant negative impact on fuel economy.

    Managing window fogging and ICE on the windows
    Using the defogger and climate control

    The defogger is standard equipment in our hybrid vehicles and can be used when the windows are fogged up or laden with ICE . However, using this equipment will come with a severe cost to our fuel economy as many of us can attest with our experiences. In any case, if you must use any of the defogging equipment do so strategically and do not forget to turn it off when its job is complete. In most scenarios you should be able to turn off the defogger after the first 5-10 minutes and then rely on the climate control system to keep the cabin environment under control. If used appropriately, the climate control should be able to monitor the temperature and humidity factors and manage the use of heat and air conditioning quite efficiently

    Typical defogging/de-icing scenario:
    1. Turn on engine.
    2. Set climate control to auto and temperature to the lowest possible level
    3. Turn on the rear defogger
    4. Do not turn on the side mirror heaters.
    5. Start moving the car as soon as the forward and some rearward visibility improve and it is enough to allow safe driving.
    6. Turn off the rear defogger as soon as possible
    7. Lower the fan rate on the climate control and do not raise the temperature beyond its minimum. Believe it not, the minimum temperature is pretty warm in a very cold day. ;)
    Other alternatives

    But what if, you could do something that prevents the fogging and icing to begin with?
    Yes, there are a multitude of options available to us and it only takes a little bit of preventative care to really make a difference. For instance, we could apply (as I do) a bit of Rain-X defogger to the interior of the windows. On the outside, we can apply a good amount of Rain-X ICE or another glass (or paint) sealant and that will enable the windows to remain clear under light snow or freezing rain. For overnight protection – especially for those vehicles that sleep outside-, you could locate a windshield blanket (protector) and all you need to do in the morning is sweep away the snow and lift it off before driving away.

    Rain-X Rain and ICE repellent, and Rain-X interior Window Fog repellent

    Windshield blanket from No2Snow

    Windshield blanket from Sno-Shield

    Windshield blanket from Wagan

    Its too cold out there. Lets just warm up the car before driving off.

    Turning the vehicle ON and idling it before driving off is never a reasonable option. It is bad for the vehicle and its emissions system, bad for the fuel economy and bad for the environment. Do not do it under any circumstances, no matter how tempting or brief it may appear to be.

    Do you have or want a remote starter in your hybrid?
    If you don't have a remote starter but you wish you had one, please do not bother looking for a reputable shop to install one in your Prius or HCH. In addition to the underlying technical challenges of a safe and viable retrofit you still have to contend with your warranties. As per the most recent information from either manufacturer, there are no such devices approved for use in these vehicles and the after market install (or attempt to install) will likely interfere with the manufacturer's warranty.
    In any case, a remote starter shamelessly defeats the design and usage goals of these two vehicles, which are predicated on using less fuel and polluting less.

    Driving your hybrid for fuel economy in cold weather

    While your hybrid instrumentation may be the source of your greatest pride during the summer months as you marvel at your skill and fuel efficiency capabilities of your hybrid vehicle, it can also be the source of your greatest disappointments in winter time driving. For those who do not drive long enough distances for the engine to warm up, it can be quite depressing to look at the poor fuel economy numbers which depending on the circumstances, can be two to three times worse that what you got in the previous summer.

    However, despite the realities of winter driving in cold weather it is important to continue driving by your instruments and avoid complacency. Yes, your cold weather fuel economy is worse but anything you do to mitigate that, will always be worth the effort in terms of fuel saved and the lowest emissions possible.

    The Hybrid Specific Operational Stages

    The Toyota Prius and the Honda Civic Hybrid II have a variety of operational modes that are mainly governed by temperature thresholds. The primary temperature inputs are acquired from the engine and various sensors in the conventional and hybrid power train systems that help determine the final behavior and performance envelope. Obviously, this article is not intended to be a detailed overview of the algorithms and I doubt many of us would be able to use this information during regular driving.
    With this said, many of us have found this temperature driven behavior perplexing and even frustrating especially when the cold weather arrives. The following tables attempt to illustrate what is going on and what to expect when the temperatures fall.

    HCH-2 Operational Stages

    First let us focus on the HCH-II as it appears to have a more complex operational profile. The following is the definition of the operational stages:


    In the table above you'll notice that Stage S3 actually defines the fuel cut-off level which allows for Auto-stop to occur. However, at very low temperatures (below -18C/0F) the Auto-stop will not occur at all.

    The following two tables attempt to identify the two primary temperature inputs that drive the transition from stage to stage:


    And lastly and more significantly, the next table defines the available transition map:


    From the point of view of an HCH-2 owner, the fourth stage (S4) is the ideal stage to be in. In this stage we can evoke a soft glide at will, we have good regenerative affinity and the EV glide and Mid 3's mode will be at their most ideal levels. In the winter months particularly during the colder days you may find it difficult to see this stage in short drives unless you use a block heater and block the front grille. On the coldest days you will be lucky if the system allows for stage S3, which includes AutoStop, and using the FAS technique will be the only way to truly prevent the ICE from idling.

    Also note the managed modes: S0 and S5. These modes can occur as a consequence of the two primary temperature inputs (Engine temp and Outside Air temp) but there are several others that begin to raise their head. For instance, MCM, BCM and DC-DC module and sensor temperatures have a very strong bearing on how quickly and severely these arrive or go away. Again, I will avoid going into too much detail here as describing these additional thresholds would only help complicate things more than they are already.

    What do these tables mean for the average HCH-II driver ? If anything, the transition map table should provide clues as to what preparations one should take throughout the entire year in order to operate on the car's most effective range - especially if one does low distance or City only driving. In the winter, one should do anything that safely brings stages S3 and S4 earlier into the picture. This means:
    • Strategically blocking your front grille
    • Using a block heater
    • Adding additional insulation to the engine bay
    • Etc
    In the summer, it is also OK to do some of these things - with moderation, of course - including using the block heater. Remember that starting the vehicle straight onto these ideal stages will be off-limits for the first 10-15 seconds after the car is booted.

    Prius II operational Stages

    In contrast to the Civic Hybrid II, the Toyota Prius II appears to be far less complex in terms of its handling of the temperature. Of course, this does not mean that the system does much less work at all. If anything, this means that the Prius does an awesome job at hiding the inherent complexities of the HSD system.

    The following tables were derived from my experiences and confirmed by the approximated findings of so many others Prius II owners. As for the Prius, the following table establishes the known states and definitions that are already well know in the public domain, but I have to admit being tempted to add a Stage S0 to indicate "Reduced to no electric MG assist" in very cold temperatures.


    The following table establishes the observed primary temperature thresholds that the system appears to be governed by.


    And finally the Temperature Transition Map as a function of the temperature ranges.


    For a Prius II owner seeking the best fuel efficiency and lowest winter emissions, the goal is to reach stage S3/S4 as soon as possible. This means that if an engine block heater is used as well as effective grille blocking the odds that you will meet that operational stage are pretty good for the broadest part of the temperature range I illustrated. This of course is subject to the length and duration of the trip but the thresholds are somewhat less ponderous and more relaxed than what Honda picked for the HCH-II.

    Since in my case the internal combustion engine will be running almost full time during the colder winter months, the typical Prius owner will benefit from a careful application of the throttle in order to keep the engine RPM as low as possible. But since the Prius does not have an OEM tachometer, I find the ScanGauge II device an absolute necessity.
    Equally important is the careful monitoring of your SoC and strategic avoidance of hard assists or even EV mode (if you manage to reach stage S4) especially when the temperatures are really low.

    What do these tables mean for the average Prius-II driver ? If anything, the transition map table should provide clues as to what strategies one should chose throughout the entire year in order to operate on the car's most effective range - especially if one does short distance or city only driving. In the winter, one should do anything that safely brings stage S4 earlier into the picture. This means:
    • Strategically block of the car's front grille
    • Use a block heater
    • Add additional insulation to the engine bay
    • Monitor your throttle input and watch your RPMs with a Scangauge II when the gas engine cannot shutdown.
    • Etc
    In the summer, it is also OK to do some of these things - with moderation, of course - including using the block heater. Remember that the goal remains to reach S4 as soon as possible. ;)

    Is there anything else that can be done to help improve our fuel economy and lower emissions even more?

    Sure there is. Consider installing an inexpensive solar panel on your Civic Hybrid or Prius. This helps, because during the winter months the power demands on your 12V battery always increase and yet the battery capacity decreases due to the colder temperature!

    Obviously, this deficit is a significant contributor to reduced fuel efficiency as many hybrid owners can attest to when their 12V batteries begin to fail. To help supplement the losses a solar panel setup for your Prius or Civic Hybrid will offer several benefits:
    1. Even if just for a few hours a day of sun or a full day of cloudy skies, a solar panel setup will help prevent dramatic and crippling losses of charge on the part of the 12V battery. Please remember that your car is slowly draining the 12V battery after you lock it and walk away from it.
    2. Maintains and extends the life of your 12V battery. Keeping a battery topped off is a sure way to ensure its long life and flawless performance for many years.
    3. Helps improve fuel economy by reducing the amount of generated energy that gets diverted from propulsion purposes to charge the 12V battery.
    4. During the summer months it can also help power an inexpensive cabin cooling setup that can further save even more energy.

    So, which car is best in harsh winter operation ?

    Sorry. I am not answering that one. For me it is sufficient to regard both cars as the very best on the market today and I am happy & satisfied with whichever I happen to be driving. ;)

    As a conclusion... and in no particular order, here are a few final thoughts:
    • Allow the higher RPM of a cold engine to power the car with the least amount of throttle input possible.
    • If you have a choice of itineraries, consider one that allows for lower speeds – even if the distance may be marginally longer.
    • Do not idle your vehicle when stopped. Shut it off or at least place it in neutral. By placing it neutral the fuel consumption rate needed for idling is often cut in half.
    • Avoid using EV or EV glides unless your SoC allows for a good fuel economy “moon shot”.
    • Maximize your regenerative opportunities over greater distances and avoid panic or aggressive stops.
    • Know your car and how it behaves under colder temperatures. Understanding the warm-up stages and their thresholds can help you decide when and how to apply the most effective setup and driving strategy. Please see the operational stage tables above.
    • Avoid operating the climate control/heater at a maximum temp setting in the first 5-10 minutes while the vehicle is warming up.
    • Watch your tire pressures. These can vary dramatically as the ambient temperatures swing downwards.
    • If possible and if you have one, plug your engine block heater in several hours before driving off. More plug-in time may be required in colder temperatures. If you don't yet have a block heater consider purchasing one and have it installed. More often than not it is worth the hassle in more ways than one.
    • Do block your front grille (intake). It is not that hard and the benefits are too significant to ignore.
    • Monitor the charge level of your 12V battery and recharge it as soon as it drops below 12V. Remember that in the colder weather the power demands increase while the battery capacities decrease.
    • Include an ice scrapper with a soft brush to remove ice and snow. A small shovel may help clear the path in case of deeper snow.
    Again, don't hesitate posting any feedback or other valuable tips. ;)


    Last edited: Nov 8, 2009
  2. msirach

    msirach Well-Known Member

    Excellent information! Clear and concise as expected!
  3. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Great! Thank you for the time spent putting this together.
  4. seftonm

    seftonm Veteran Staff Member

    Great article Manuel, and there are plenty of tips that a non-hybrid owner can apply as well. I've discovered that on cold days (like -30C) with a cold windshield, my -45C rated washer fluid can still freeze on my windshield. I am thinking that the alcohol in the fluid evaporates, leaving behind only the water which quickly freezes. Either that or the fluid is optimistic with its rating. Does that ever happen to anyone else? I usually use the cheap stuff from CT or Wal-Mart when it goes on sale and am wondering if the brand has something to do with it.
  5. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    If it is blue, it is usually very diluted around here. I like to use something called "Purple Power" -- I've had good results with it.
  6. laurieaw

    laurieaw Sorceress of the North

    since my portable garage was a dismal failure, i think i will look into one of those windshield blankets........
  7. w4wfm

    w4wfm Well-Known Member

    Excellant article! Thanks for the effort.

    It raises one question for those of us down south. For partial blackage (50-60%) do you recommend blocking the top or the bottom? Or does it matter?

    Thanks again,
  8. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Block the top first, for aerodynamic benefit. You can block it completely, even in the heat of summer. (notice that I'm in Texas...) There is more than enough cooling capacity with only the lower opening.

    Try partial blocks on the lower once the upper is covered.
  9. Jess

    Jess Well-Known Member

    Another fantastic article MSantos.

    I had the same question concerning blocking 50% of the grill. Did you block the upper or lower when you ran the tests?

    I blocked only the lower today and found much better results than having the full grill blocked.

    Thanks again.
  10. msantos

    msantos Eco Accelerometrist

    Hi Jess and Frank;

    I actually block the bottom part on the grille first and then proceed to block the remaining portions above. The main reason I do so is because the bottom parts make up the longest spanning applications of the foam tubing and not surprisingly, also happen to be the most difficult to insert and remove.
    Not that the whole setup is difficult at all, but the upper segments are smaller and hence easier to insert and remove as required.

    Also according to my observations over the last few years, manipulating the bottom first yields the most dramatic results on the HCH as well as the Prius.

    However, I do agree with Andrew regarding the aero-dynamic reasons to do the top first especially if you have a daily highway routine. Since I am 100% city there's no advantage to start from the top first and only the convenience factor seems to matter to city slickers like me. :rolleyes:

    By the way: Keep checking this thread as I will be adding the Warm-up/Operational stages for both the HCH-II and the Prius-II... sometime this week or weekend (or as time permits).


  11. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Manuel -- that sounds like an excellent addition! Please add a response post when you do so that this thread pops up in the updated listing and people take another look.
  12. Kacey Green

    Kacey Green Well-Known Member

    Yes, please post so the subscribed get an email too!
  13. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member


    Any opinion on supplementing a coolant heater with an engine oil heater?

    Wolverine is one brand I've found online. Their typcial heater is a rubberized heated pad, that is bonded to the underside of the oil pan via peel-and-stick adhesive, and then similarly to a coolant heater there is a 110 volt power cord run out through the front bumper grill.

    Thanks in advance.
    Last edited: Nov 28, 2008
  14. msantos

    msantos Eco Accelerometrist

    Hi Mendel;

    That is a pretty good question and the Wolverine unit sure looks promising for a lot of folks who either cannot or do not want the hassle of a block heater installation.

    Here are my thoughts:

    In order for these "pads" to be effective they must (ideally) be installed in a clean and relatively flat surface. This is especially true for the high powered models.
    It appears that the best ones for small cars are rated for 200-250 Watts (??) and seem to do a good job of "baking" the oil... they seem to do it for roughly half the electrical load. So yes, at first these would appear to be more efficient than your typical EBH rated at ~400 watts.

    Frankly, I don't know if a wolverine pad would give me too much of an advantage. I noticed that in very cold days the surrounding air just steals much of the heat produced by the block heater and things only get worse (with increasing diminishing returns) the longer the unit remains plugged in. But the combination of the two would definitely heat up the engine block faster for sure. Also, a worlverine pad would not be a problem for me since I do not drive on gravel roads nor do I go off-roading. :D

    Then again, I am of the opinion that water remains a better thermal conductor and because of that I still see the EBH as a device with greater merit. Just my opinion. :)


  15. skoh

    skoh New Member

    Great owner's manual for the winter!

    If I may add, if you are getting your oil changed at a dealership, make sure to specifically request the 0W-20, otherwise you may get the "standard" oil that is in their bulk tank which more than likely is 5W-20 or 5W-30.

    Toyota & Honda dealerships should have 0W-20 in quart bottles and many dealerships now have 0W-20 in bulk. Just make sure you ask for it.
  16. msantos

    msantos Eco Accelerometrist

    Hi all;

    HCH-2 temperature dependent operational stages added. Prius temp stages coming up (they're a bit simpler) ;) ...

    Hi skoh:

    I often suggest people use the 0W20 oil requirement as the ultimate technical litmus test on whether a dealership is worthy of any post sales business. You should not have to ask that they use 0W20 at all. But if this is the only way they will do the right thing, then unless you do not have a choice look for another dealership that is not only more technically competent but also more concerned about the impact a lesser oil will have on your car's FE.


  17. Jess

    Jess Well-Known Member

    Great charts, MSantos. All these behaviors of the HCHII cold, I have witnessed. However, it's nice to know, now, why and/or when they may occur.

    I appreciate you "opening our eyes" to the reasons for these behaviors. I used to think it acted like it had a mind of it's own and therefore out of my control. I guess it still is somewhat out of my control though, but not as much as I had previously thought. ;)

    Thanks again,

  18. bruceha_2000

    bruceha_2000 Member

    Great article Manuel. But, of course, I have a question or two. :)
    1. At the moment we are sitting in the "early morning sub freezing, daytime high low 40s F" Is "66%" blocking OK or do we need to be on the safe side (no scan gauge) and stick to 50%?
    2. Your chart was for 10 - 15 minute commute. What about a LONG interstate drive. Same temps as above. Does the higher speed force more cold air through so a 75% block would be preferable?

    At the moment, I have both cars blocked upper and 1/2 lower. After seeing your chart, looks like I better take out one of the uppers.

  19. msantos

    msantos Eco Accelerometrist

    Hi Bruce;

    That is a good question.

    I would still consider getting a Scangauge II at some point since one never knows what is truly happening to the engine temperature. Lets say you leave in the morning and it's cold - no problem. You return in the evening and things are warmer, this could be a problem.

    Still, I would venture to say you could block 75% without much concern if the ambient temps are closer to the low end of the the boundary I identified in the chart (32F).
    Things really begin to warm up as you approach the upper boundary (59F) and at that point the engine temps can easily exceed 194F after a while - which is NOT a good thing over the long haul.


  20. msantos

    msantos Eco Accelerometrist

    Hi All;

    The Prius II temperature/stage tables were added.



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