Tips on Stretching Your Non-Hybrid Car's MPG

Discussion in 'Start Your Journey Here' started by SkeeterVT, Jun 11, 2007.

  1. SkeeterVT

    SkeeterVT Member

    I own a 1999 Saturn SL1 sedan. With prices for hybrid cars still out of reach for people of modest incomes like me, I long ago decided to take every step imaginable to make my standard gasoline-powered car more eco-friendly -- and save money on fuel in the process.

    The first step in making your vehicle more eco-friendly is knowing its specifications. Every step you take thereafter has to be based on what your vehicle is capable of. In my case, my Saturn has a four-cylinder, 100-horsepower, single overhead cam engine. It's well known that four-cylinder engines are more fuel efficient than six-cylinder and eight-cylinder engines. And the lower the horsepower, the less fuel is required to power it.

    Some of the steps that I've taken are fairly simple and can be applied to just about any vehicle you drive, such as:

    1) Routine maintenance. Maintain a regular oil and filter-change schedule. Also rotate your tires at every oil change to balance tread wear. Make sure to have your vehicle's wheel alignment adjusted at least once a year. Ditto a coolant flush and automatic transmission treatment. Keeping a regular maintenance schedule should be a no-brainer, especially if you want your car to last longer than the average ten-year lifespan of most vehicles today.

    2) Making sure that your tires are properly inflated. Too little pressure can not only cause a loss of fuel economy, but can also wear your tires out faster. Too much pressure can also wear out your tires faster -- and particularly during the hot summer months, increase the risk of a blowout. Check the side of the tires to see what the maximum pounds per square inch (PSI) rating is. A good rule of thumb is to inflate the tire to nine or 10 PSI below the maximum (Example: if the maximum PSI is 44, inflate the tire to no more than 35 PSI in winter, 30 PSI in summer).

    3) Using cruise control, if your vehicle is equipped with it, will save you considerably in both fuel economy and wear-and-tear on your car. Another advantage of cruise control: you'll never have to worry about getting pulled over for speeding. Avoid jack-rabbit starts and sudden stops. IMPORTANT SAFETY NOTE: Do NOT use cruise control during the winter months if there is snow or ice on the road.

    4) Set strict speed limits and stick with them, whether your vehicle has cruise control or not. I never drive faster than 60 miles per hour on the interstates, 40 or 50 miles per hour on secondary highways, depending on the posted speed limit, and 30 miles per hour on city streets. Driving over 60 miles per hour reduces your vehicle's fuel economy. Always drive well below your normal driving speed in inclement weather, especially during the winter months.

    5) Contrary to popular belief, all gasolines are NOT the same. Always use a high-quality, regular-grade (87 octane) detergent gasoline that cleans your vehicle's fuel injectors. Otherwise use a fuel additive, such as STP Gas Treatment, year-round to keep the injectors clean and prevent wintertime gas-line freeze. Don't waste your money buying mid-grade (89 octane) or premium-grade (93 octane) gasoline, unless your vehicle was made before 1990. Consumer Reports magazine recently graded gasolines by quality and fuel economy. You can visit for the results. I always add a fuel additive year-round to keep my Saturn's fuel injectors clean and prevent wintertime gas-line freeze.

    6) If your vehicle is equipped with air conditioning, use it only during the daytime hours in the summer. To obtain maximum cooling with minimum reduction of fuel economy, keep the windows and air vents CLOSED and the fans set to lowest speed. The recirculating air will get cooler much more rapidly than if hot air from outside is drawn in. Don't use the A/C at night, unless the nighttime weather is oppressively humid. TIP: If you're forced to park your car in an area that's exposed to the sun, open all your vehicle's doors when you return to let out the hot air built up inside, then start the engine and turn on the A/C before closing the doors.

    7) When you park your vehicle, always turn off the A/C about 30 seconds BEFORE shutting off the engine to avoid rapid condensation that can cause rust and damage your vehicle's engine. If climbing a steep hill, turn the A/C OFF to reduce strain to the engine. Turn it back on when you're reached the top of the hill.

    Got any other ideas for making your standard gasoline-powered vehicle more fuel efficient and eco-friendly? Post them here.

    -- Skeeter Sanders
  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Skeeter:

    ___Welcome to CleanMPG!

    ___With regards to non-hybrids, we go a bit further then what you have posted above. I highly recommend that you start reading the articles and a lot more should be revealed in your quest for higher fuel economy and lower emissions …

    ___Good Luck

  3. pumaman

    pumaman Well-Known Member

    One thing you'll get definite disagreement on is with the tire pressure recommendation
    of 9 - 10 psi below the max sidewall pressure. For example, the max sidewall pressure listed on the tires on my daughter's car is 35. So 9 less would be just 26 psi, or 6 below the car manufacturer's recommendation of 32. That would be dangerously low IMO. I feel much better putting in 35psi as opposed to 26...
  4. JimboK

    JimboK One owner, low mileage

    I'm with Pumaman. Significant underinflation probably causes a greater risk of blowout than overinflation. Underinflation stresses the sidewall causing heat buildup and increases the risk of eventual failure. I was in the retail tire business years ago, and I never saw or even heard about a blowout attributed to overinflation; I saw many from underinflation. The theoretical concerns back then about overinflation were a blowout from a hard hit on a curb, pot hole, etc., and as you suggest, accelerated wear in the middle of the tread.

    I acknowledge that tire technology probably has changed somewhat in the 25 years since I was in the business. But significant underinflation is still a bad thing, fuel economy aside. Even if 10 PSI below the sidewall pressure is safe, it leaves less margin of error for a slow leak from a road hazard or the inevitable normal loss of air.
  5. SlowHands

    SlowHands Hypermiling Ironman

    We've pretty much always kept our air pressures at a bit more than mfr. recommended, and the only time we saw center wear was with a lot of high speed (70-80 mph) driving. Specifically, we had a Dodge that was used only in town for years by Gramma, tires wearing a bit on the outside if not dead even. When I started using it for cross country travelling, it wasn't too long before I wore the centers down. Once it was back to city use, it wore the outers again and came back to even wear... kept the pressures at the mark all the time. So right now, with the lower general speed in the Rangers, and higher pressures, I'm pretty confident of even wear.
    The only time I went below rec pressures was for Ice Racing...:D
  6. SkeeterVT

    SkeeterVT Member

    I'm afraid that we'll have to agree to disagree on this matter. . . It's been my experience that if you inflate your tires to 5 PSI or less below their maximum limit -- especially during the hot summer months -- you increase the risk of a blowout.

    As you drive, the PSI inside the tires always expands. During the winter, it expands by an average of five PSI. In the summer, the pressure can expand by as much as 10 PSI, depending on the size of your tires. On extremely hot days (over 90 degrees), your tires' pressure can go up by as much as 15 PSI -- especially if you're driving at highway speed.

    Even if your car sits parked for hours during the day without having been driven, your tires' pressure will still go up merely from direct exposure to the sun. Therefore, it is imperative that you give your tires greater "breathing room" during the summer months by inflating them no greater than 9 PSI below their maximum pressure limit.
  7. johnf514

    johnf514 Zoom? Try Glide!

    SkeeterVT, I do see your point with worries of a blowout at max sidewall. However, I can give you my experiences with this as I am a FL driver.

    A year ago, I was commuting twice weekly to Orlando during the summer, a 70 mile drive. I did much 60+ MPH driving with a few twisty backroads at 45-50 MPH. My tires were 25K+ miles old, running at 45 PSI (cold) and I drive a Ford Taurus. Keep in mind that this is during the summer, and the road temps can exceed 100F easily.

    I drove 5000 miles that summer on those tires under those conditions and not once did I see any sort of tire failure. At the end of the summer when I replaced them, the mechanic was impressed at the integrity of the tires when I told him about how they were run.

    Tires are over-engineered, plain and simple. While I do not recommend vastly exceeding max sidewall, I do promote inflating to at (or a few PSI under, to account for warm-up) max sidewall. Tires are designed to run efficiently and effectively at this pressure, and will not wear or risk blowout this way.

    The major risk to tires is *underinflation* as it compromises the sidewalls of the tire and causes flexing, cracking, and eventual failure.

    Just my experiences. :)
  8. tarabell

    tarabell Well-Known Member

  9. JimboK

    JimboK One owner, low mileage

    Skeeter, please help me understand what you're saying. My tires' max sidewall pressure is 44. Are you suggesting that my risk of a blowout is greater at >39 PSI than at 34? Or for those whose max pressure is 35, that the risk is greater at >30 than at 25? If so, where is your evidence? Please describe this experience you cite.

    Maximum sidewall pressures are cold pressures. Tire manufacturers account for the heat buildup from normal driving in their recommendations and, in John's words, in their over-engineering.
  10. Walter

    Walter Well-Known Member

    How To Read A Sidewall

    Hi SkeeterVT, Here's a Dunlop link:
    How To Read A Sidewall
    that defines the max pressure on the sidewall as MAX COLD PRESSURE.

    "As you drive, the PSI inside the tires always expands." This is correct, but for normal operation, this rating takes this into account. For extremes of temperature you might have to adjust this, but this would be setting the cold pressure on a glacier (20F) and driving to the desert (air 125F).

    For most cars running the tires at this max pressure won't be a safety problem; there will be a harsher ride. For a few SUVs or pickups with poor suspension design and underrated tires, there could be safety problems: was it Ford Explorer that had all the blowout problems?

    Some cars have different recommended pressures front and rear. I'd be a bit careful to make sure the handling didn't deteriorate as you raise the pressure.

    Your other recommendations are a good starting point. Some people here go beyond that.

    Anyway, welcome to the group!

  11. pumaman

    pumaman Well-Known Member

    The only time I've blown out a tire that was inflated to max was when I took a turn too tight and caught the curb. No fault of the tires, bad driving on my part. As mentioned by others, blowouts during normal driving happen to underinflated or damaged tires.

    You really don't have to do anything differently due to the time of year either. Let me put it this way. If putting in the max pressure as recommended by the tire manufacturer made it likely a tire would blow out when the weather gets hot, then the manufacturer would be sued on a regular basis because of it. Doesn't happen that I'm aware of. They would not put themselves in that position. They design the tires to handle that pressure during any type of conditions short of driving through a lava flow. Kind of like how a climbing rope rated to hold 300 lbs, when new, will actually support three times that.

  12. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    The tone of this, your first post, is a problem. You show up with a list and put on the air of an authority on the subject. Problem is, that subject is the whole reason for this site. We have been discussing these same points here for months / years. Look at the top of the screen. At this point, users on this site have saved 63,000 gallons of gas compared to the EPA estimates. That's a LOT of experience. We also have logs of our fillups and mileage posted, so you can see how techniques are working for each one of us. We have discusses some items, including tire pressures, with manufacturers. What's your background and experience?

    About the points you listed, here are my responses:
    1) Routine maintenance.
    - Yes. Absolutely.

    2) Making sure that your tires are properly inflated.
    - Yes. Finer points already discussed above.

    3) Using cruise control.
    - Yes to a point. I can get 5-10% better than cruise control myself, while maintaining the exact same speed. If I let the speed rise and fall with the terrain (DWL), easily 20% better than cruise control.

    4) Set strict speed limits and stick with them.
    - I go with the flow of traffic except on highways. Around town, 35, 45, 55 mph, fine. It's above 55 that aerodynamic drag really starts to hurt you. On the highway I'll go 60 or with the flow if it's HEAVY traffic - safety first!

    5) Contrary to popular belief, all gasolines are NOT the same.
    - If your car needs higher, give it that. Otherwise, no. The point about earlier than 1990 - what???. Perhaps you're referring to the way computer-controlled fuel-injected cars have knock sensors that will adjust the ignition timing if the grade is too low. Other than that, I don't know. Anyone have evidence or studies on this?

    6) If your vehicle is equipped with air conditioning, use it only during the daytime hours in the summer.
    - Yep. Gas robber, that AC. When you park, use one of those sun reflectors. It keeps the air in the car cooler, protects the interior from sun damage, and lowers the surface temperatures (steering wheel, seats, seatbelt) which lowers the apparent temperature even more.

    7) When you park your vehicle, always turn off the A/C about 30 seconds BEFORE shutting off the engine to avoid rapid condensation that can cause rust and damage your vehicle's engine. If climbing a steep hill, turn the A/C OFF to reduce strain to the engine. Turn it back on when you're reached the top of the hill.
    - Sure, I'll agree.

    We have a whole list of Articles about various methods of saving gas.
    Last edited: Jun 12, 2007
  13. HCHCIN

    HCHCIN Well-Known Member

    I would also have to disagree with the sentence: "Don't waste your money buying mid-grade (89 octane) or premium-grade (93 octane) gasoline, unless your vehicle was made before 1990."

    The year of the vehicle has nothing to do with whether high-octane fuel is used. High-octane fuel is recommended in cars with high-compression engines to prevent early detonation within the cylinder, which produces "pinging" and can harm the engine. My last car, an Audi A4, actually had sensors and algorithms that changed the engine's timing (and thus performance) if lower-octane fuel was used.

    In short, read your owner's manual -- if it advises high-octane fuel, it's best to use it. Otherwise, put in the cheap stuff. --RN
  14. WriConsult

    WriConsult Super Moderator

    I did that once too, back when I lived in Seattle. At many corners there, the curb edges are protected by an iron strip. Sometimes those metal strips get bent and end up sticking out a bit at the end. I caught one of those ends with my tire once while taking a corner too tight and it went BOOM!

    Funny part is, I was in a part of town with a high crime rate where gun violence is not unknown. There was a guy about half a block away walking down the sidewalk, and when my tire blew he hit the ground. Poor guy must have thought he was getting shot at.

    Legend has it that bicycle tire manufacturers inflate tires until they explode, then divide the number by 2 (which means 1/4 as much air) and stamp that as "max pressure" on the sidewall. I'd guess automobile tire manufacturers build in an even bigger safety margin than that.

    I believe climbing ropes are rated to handle a static load of 4000 pounds!
  15. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Skeeter:

    ___You would be shocked as to where burst pressures on today’s tires actually are. Let us just say they are far beyond 100 psi and running a max sidewall of 44 #’s as measured in the coldest point on earth and driving them to the hottest will not cause you any issues whatsoever. Just the way it is.

    ___My 44# max sidewall Michelin MXV4 +’s have over 90K at 60 + cold if that helps?

    ___Good Luck

    Last edited: Jun 12, 2007
  16. diamondlarry

    diamondlarry Super MPG Man/god :D

    I have run 60+ psi in Goodyear Assurance Comfortread's on my Saturn for several thousand miles, including three 550 mile trips at 70 mph in 80*F heat and had NO blowouts and NO uneven wear. In fact, one of the long trips was at 70 psi.
  17. johnf514

    johnf514 Zoom? Try Glide!

    You have tires with 90K miles on them? Please tell me that's KM! :eek:
  18. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi John:

    ___Nope. And they have another 20K + in them if I want to push it ;) 4/32 front and 5/32 rear from their initial 11/32 when new.

    ___Good Luck

  19. johnf514

    johnf514 Zoom? Try Glide!

    Wayne, I'm impressed! Not only is that a testament to the tires, but your driving! :D

    Like you need any more praise. ;) Well done!
  20. brick

    brick Answers to "that guy."

    The original reason that Prius owners started recommending a cold inflation pressure of 42/40 psi f/r was to increase the life of the stock tires (Goodyear Integrity). They had problems with the edges rounding off at stock specs and do significantly better when inflated close to the max sidewall The fuel economy bonus was discovered as a byproduct in the case of that particular community. Mine have hardly a hint of wear, uneven or otherwise, at 46/44psi and approaching 10k miles.

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