Do not use quick accelerations or brake heavily: This reduces fuel economy by as much as 33 percent at highway speeds and 5 percent around town. EPA tests do not account for this kind of vigorous driving.
Do not idle excessively: Decreases average FE. The EPA city test includes idling, but drivers that experience more idling experience lower MPG.
Do not drive at higher speeds: This increases aerodynamic drag (wind resistance) and mechanical friction which reduces fuel economy. The EPA test accounts for aerodynamic drag up to highway speeds of 60 mph, but drivers often exceed this speed.
Cold weather and frequent short trips reduce fuel economy, since your engine doesn't operate efficiently until it is warmed up. In colder weather, it takes longer for your engine to warm, and on short trips, your vehicle operates a smaller percentage of time at the desired temperature. Note: Letting your car idle to warm-up doesn't help your fuel economy, it actually uses more fuel and creates more pollution. Drive to your furthest destination first and then as you are heading home, stop at the closer destinations in order from furthest to closest as the car is warmed up for longer portions of your drive.
Remove Cargo or cargo racks: Cargo and/or racks on top of your vehicle (e.g., cargo boxes, canoes, etc.) increase aerodynamic drag and lower FE. Vehicles are not tested with additional cargo on the exterior.
Do not tow unless absolutely necessary: Towing a trailer or carrying excessive weight does decrease fuel economy. Vehicles are assumed to carry three hundred pounds of passengers and cargo in the EPA test cycles.

Minimize running mechanical and electrical accessories: Running mechanical and electrical accessories (e.g., air conditioner) decreases fuel economy. Operating the air conditioner on "Max" can reduce MPG by roughly 5-25% compared to not using it.
Avoid driving on hilly or mountainous terrain if possible: Driving hilly or mountainous terrain or on unpaved roads reduces fuel economy most of the time. The EPA test assumes vehicles operate over flat ground.
Do not use 4-wheel drive if it is not needed. 4-Wheel drive reduces fuel economy. Four-wheel drive vehicles are tested in 2-wheel drive. Engaging all four wheels makes the engine work harder and increases crankcase losses.
Maintain your Automobile: A poorly tuned engine burns more fuel, so fuel economy will suffer if it is not in tune. Improperly aligned or under inflated tires can lower fuel economy, as can a dirty air filter or brake drag.
Try to purchase high BTU content gasoline if available: Fuels Vary in Energy Content and some fuels contain less energy than others. Using oxygenated fuels or reformulated gasoline (RFG), can cause a small decrease (1-3%) in fuel economy. In addition, the energy content of gasoline varies from season to season. Typical summer conventional gasoline contains about 1.7% more energy than typical winter conventional gasoline.
Inherent Variations in Vehicles: Small variations in the way vehicles are manufactured and assembled can cause MPG variations among vehicles of the same make and model. Usually, differences are small, but a few drivers will see a marked deviation from the EPA estimates.
Engine Break-In: New vehicles will not obtain their optimal fuel economy until the engine has broken in. This may take 3-5 thousand miles.

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Replies to This Discussion

Those are all good ideas.
The car we traded in for our Smart Car was a 2005 PT Cruiser convertible. It averaged around 22 MPG. NOT GOOD! I have always tried to be a conservative driver mileage wise, but with that car, I made it into an art. Now that we have the Smart Car, I am continuing the same patterns. I try to take my foot off the gas well before any stop signs, or curves, etc., when I know I am going to have to brake. Less braking means better MPG! Of course, I do this safely & I don't "hold up" traffic in order to do it.
Anyone aware of the Drive 55 project?
I tend to agree with the theory. Though trying to drive 55 around here can illicit road rage from fellow drivers. Heck. Doing 60 in a 60 mph zone when everyone is else is doing 70 or better can be dangerous. And it seems few in the DFW area actually drives the speed limit.
The premise is to save gas {and the environment} by only driving 55 mph. For some of the members there the hope is to get the speed limit lowered. But without the speed limit lowered some are driving 55 anyway.
My first week in the smart car I tried to drive it like I did the Audi without thinking. I was so used to the audi's ability to accelerate quickly, take hills, and stop quickly that I didn't realize just what bad habits I had gotten into until I started driving the smart car.

My 2nd week into the smart car and I've significantly improved my MPG just by accelerating and decelerating more slowly.
Don't forget proper tire air pressure to maintain best gas mileage. I bought a digital air guage (about $15) and each week check the tires when they are cold (first thing in the morning). Tire pressure varies greatly with air temperature. If the car has been driven recently expect the air pressure to be higher than when cold.

Example: Front tires 29 PSI (cold 55F) - 32 PSI (warm)
I notice a great difference in Michigan where our ambient temperature varies from subzero to quite hot (90's). I try to keep them at 29 PSI (based on 45F - 55F).

Running them with less air will result in lower mileage and excessive tire wear.
Running them with too much air will decrease handling (poor 'grip') and also increase wear.
Expect tires to naturally lose air over time so regular checking and checking before a long trip is advised.
Some people pay to have nitrogen fills (may keep pressure longer) but I don't bother due to the inconvenience of getting regular fills. I keep a small air tank around so that I can 'top up' the tires as needed. If you noticed that a tire is a 2 PSI too low - then take a note of the PSI and when you find a gas station with air (good luck) take another reading and then add the 2 PSI to that reading to get the tire to the correct pressure. Depending upon the temperature and distance you will notice an increase.
"... Running them with less air will result in lower mileage and excessive tire wear.
Running them with too much air will decrease handling (poor 'grip') and also increase wear.
Expect tires to naturally lose air over time so regular checking and checking before a long trip is advised. ..."

I never check the tire pressure! For a small price I have my tires filled with a gas they use in airplane tires. So it keeps a constant pressure all year long.I understand, your tire dealer in the US can offer it too.


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