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I just acquired my first hybrid, a 2010 Prius and I'm wondering how to approach the mileage numbers you guys seem to be getting. I live in the hilly edge of the finger lakes region of New York and every road seems to go either up hill or down. I got pretty good at hypermiling my manual focus up to around 40% better than EPA with lots of ICE-OFF coasting, but using similar technique with the prius (gentle power going up the hills, just enough to hold 50mph, and ICE-OFF coasting down) barely gives me EPA numbers. :mad: I try to keep it out of the red PWR band on the HSI whenever possible. Of course it's still only 20 degrees F.. is that the problem? The car is brand new with only about 500 miles on it.

Hi BWarchitect;

At those temps I would consider doing at least a partial block of the front grille (the bottom part first). In my experience, the FE can appear atrociously low before the engine warms up but if you give it a hand at speeding up the process, the HSD system will begin to thank you much earlier.
Learning about the warm up stages for the Gen III Prius will also help you understand what other things you can do earlier that will help you induce a neutral (putting in N) or soft-glide (using the accelerator) glide pattern for the gentler descents.

Also consider the installation of block heater. When used properly (even all year around) it will also help produce better results.

Getting a scangauge would also help a whole lot since the built-in instrumentation does not always tell you the truth, especially as far as engine off conditions are concerned and since you are trying to get a handle on this, I suggest you consider adding one to your Prius.
Of course, a scangauge can do a lot more too especially as you begin to tackle and manage energy flows in particular what goes into the battery pack as well as what comes out.

Lastly, tackling hills does not always lead to bad FE. All we have to do is some of the above, airing those tires up, STRATEGIC use of EV, plus some mastery of DWL which takes time and practice. Beating the EPA on hills will become quite easy after a while. :D

Cheers;


MSantos

Hi BWarchitect.

There will be a bit of break-in.

But yes, temperature kills the numbers. I go from low-40s in coldest winter to over 60mpg at peak. Click on the mileage log in my sig to get a sense of how much it varies.

Also bear in mind that the Prius builds in some of the gas-saving techniques hypermilers use so it's harder to beat the EPA by large amounts. On the plus side, it means you get efficiency with less work.

Like you I have a hilly (undulating) commute. I don't get too much chance to DWL on my commute but do it where I can to stay out of the power zone. With people behind me I have to go into the power zone multiple times on my commute to maintain PSL, some blasts shorter than others.

Keep the tire pressures up.
Install a grille block to help warm-up and cut a little drag.
If your car is garaged and you can plug in, having an engine block heater installed will also help warm-up in cold temperatures.

This site advises that you obey all traffic laws. Do you?

All cars have problems getting good fuel economy under cold temperature conditions, especially if your trips are short. I've read the Prius engine always runs when you're traveling faster than 42 mph, so try to keep your speeds below that so your glides are more efficient.

I took a Prius on a test drive, and managed 75 mpg on an 8 mile round-trip going over a steep 100' hill midway The salesman warmed the car up for a few minutes, but that was in 35 degree weather.

I had the opportunity to drive a Prius on several 20 mile round-trips inside Bryce Canyon National Park with another volunteer. Temperatures were typically 50 degrees, and the drive involved an 800' elevation gain one-way, and a corresponding drop on the return drive. Speed limit was 40 mph most of the drive, with about 1/3 of it 35 and 25 mph PSLs. My buddy, a non-hypermiler, averaged about 55 mpg. I averaged about 62 mpg.

I used a P&G routine I saw on YouTube. Basically, you accelerate to 42 mph, and modulate the gas pedal to keep your engine/battery power display black - no power being used from the battery or the gas engine, and no power being regenerated from the wheels/alternator - except on the steep hills, where I forced regeneration. When speed drops to 20 or 25 mph, you accelerate gently back to 42 mph, and repeat.

All cars have problems getting good fuel economy under cold temperature conditions, especially if your trips are short. I've read the Prius engine always runs when you're traveling faster than 42 mph, so try to keep your speeds below that so your glides are more efficient.

The 3rd Gen runs the engine above 45mph. Above 45mph the closest you can get is SHM.

Well, there is high-speed N-glide. If you shift to N the car remains in the mode it was before the shift. So you can shift to N while in a glide and then gain speed down a hill and glide at more than 45mph. However, the limit is there to protect MG1 (?). If you go faster you risk damage. Knowing that Toyota are conservative with their setting, people will do occasional high-speed N-glides but if they do they limit their speed, commonly under 60mph.

Newer hybrids from other manufacturers seem to have a higher glide limit, and the Prius PHV has 62mph in EV mode. Wayne also recently mentioned that it seems that Ford have overcome the speed limitation in the design to be used in the Focus HEV, possibly with addition of a clutch.


I took a Prius on a test drive, and managed 75 mpg on an 8 mile round-trip going over a steep 100' hill midway The salesman warmed the car up for a few minutes, but that was in 35 degree weather.

Ken@Japan on PriusChat advised that short 6% inclines followed by long 2% declines are great for Prius economy. That's consistent with general Prius strategy of gliding as much as possible.

For temperature, to me it seems it's all a wash below 20F and then I can see obvious economy improvements above that. Now that my morning commutes are in the 20s and my afternoon commutes is more likely to be at or above freezing I'm back over the EPA, and that with some of the miles non-hypermile, driven by or with my wife.

Thanks to all for helpful comments- In the first week I haven't checked the air pressure yet, 'cause I'm a wimp and it's cold out, but I will. And it sounds like I should try some Mobil 1 oil also for less internal resistance. Not sure how to make a grille block. At least it's supposed to be a bit warmer this week. Overall I love the car. Great forum!

How about this:


A Hybrid Owner’s winter survival guide (http://www.cleanmpg.com/forums/showthread.php?t=17560)





http://www.cleanmpg.com/photos/data/500/MS_Prius3G_FrontGrilleBlocked.jpg

Cheers;

MSantos

Well here's an update, 4 months into my Prius ownership experience. Now that temps have warmed up and the car has about 5,000 miles on it, I can easily get 60 mpg or better on a trip, sometimes up to 70 if I'm not using A/C. With the variations in our trips and my wife as primary driver (non-hypermiler) we average around 54 per tank. I'm very happy with that!

optional equipment which would help
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a ScangaugeII GPH gauge


the technique
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In a continuouslly steep hilly road - it is more fuel efficient to accelerate the Prius on the downhill from about the middle of downhill slope increasing your momentum for going up hill then At the bottom of the two hills the Prius speed should be about 10 mph to 15 mph above the desired speed that the prius should be at the top of the next hill reducing your throttle to the middle (underneath the "ECO" pill label) to 3/8 of the way on the HSI/ECO bar (basically running the ICE at about 1.5kwh that is at about 1.0 to 1.2 GPH if you have a ScangaugeII). Having the ICE and the EMG on during the uphill insures that the uphill climb does not deplete the battery power. As the Prius goes uphill loosen up on the throttle gently alllowing the Prius velocity by 10mph to 15mph gradually as it makes its way uphill. As the Prius pass the crest of the top of the Hill of the next hill apply battery power only until the Prius is pointing downward on the slope of the next hill before repeating process.

theory
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Why does this work? It works because it takes less power to push a car downhill than uphill because of gravity helps on the downhill and hurts on the uphill. It also works because given a neutral-flat surface it always takes more energy to move at a faster speed than a lower speed ( cost of acceleration). Increasing the average speed going downhill produces more speed for less fuel. Slowly decreasing the average speed (but not stopping) going uphill and additional momentum (initial force) gained from going downhill will cost less fuel than attempting to maintain or accelerate to a higher speed when going uphill.

caveats
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The fuel improvement for using this technique varies depending on the initial speed achieved on the bottom of the two hills and the initial and final velocities at the top of both hills . In addition, the length of the downhill and uphill road segments will also effect the implementation and the fuel efficiency gained by this technique. The longer the down hill and uphill road segments are the easier this technique is to use. The shorter the downhill and uphill road segments are the more difficult it is to apply this technique.

Implementation
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I've tested this technique on Norbeck Road (Rt 28) in Montgomery County MD going westbound from Silver Spring (Georgia Ave Rt 97) to Rockville ( Rockville Pike, Rt 355) on a particular downhill uphill section that starts at Bauer Driven and ends at Avery Rd. From Bauer Drive if I haven't stop at the traffic light there I am normally going about 32 mph. As the Prius goes downhill I increase the throttle to about 1.0 GPH until the Prius is going about 50 mph and maintain this speed as I pass bottom of the two hills where the road passes over RockCreek Trail ( the stream that passes under the road) then I gradually loosen the throttle so the Prius decreases in speed to about 30 mph as it gets Avery Rd. About midway between the top and the bottom of the uphill segment the Prius is speeding along at slightly over 40 mph. If the Traffic Light is green on Avery Rd keep the speed above 28 mph to pass the traffic light. If the traffic light is red or yellow on Avery Road then I allow the Prius to slow down even further before stopping. The next traffic light is at East Gude Road which is more often red than green. The west bound road segment from Avery to East Gude is a gentle slope downhill. If I have to stop at East Gude Road I allow the Prius slowly decrease in speed from 30mph to about 12 mph or less depending on the traffic. If the next traffic light at East Gude Road is green and I can time the Prius speed to pass through it I will increase my speed.

hth

Walter Lee
2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats
Yokohama Avid S33 ( front 50 psi, rear 48 psi )
ScangaugeII ( AVG, MPG/FwT, SoC, GPH)
Odeometer +14000 miles, overall 59 mpg calculated at the pump, E10 gasoline
best tank 66mpg ( 602 miles, calculated mpg - MFD mpg higher, 5/31/2011, tire pressure 48/44 psi, no grill blocking)
worst tank 52 mpg (432 miles calculated mpg - MFD mpg higher , 12/27/10, tire pressure 40/38 psi, 100% grill blocking)
dc/md/va area

Hi BWarchitect:

With gasoline here in IL at $4.00 per again, I know about 5-million people that would be ecstatic with 54 mpg!

And both congrats and thank you for purchasing the number one fuel miser available :)

Wayne

Hi BWarchitect! All it takes is a little patience through the learning curve (and temps!)

So, it sounds like it's safe to say that you have achieved the proverbial "Prius Grin!"