1. Keep your vehicle well-maintained
A car in poor running condition will use more gas than one that has been tuned up. According to this checklist at Advance Auto Parts, a dirty air filter can reduce gas mileage up to 20%. They also note that spark plugs in poor condition can reduce gas mileage up to 12%.

2. Keep tires properly inflated
Underinflated tires aren’t just dangerous — they devour fuel economy by as much as 25%! (I know this from experience — whenever I notice a drop in MPG, my tires are usually low.) Overinflated tires aren’t efficient, either. Also keep your tires balanced and in alignment.

3. Optimize your travel
Consolidate trips: If you know you have to buy groceries, take your clothes to the dry cleaner at the same time, and then drop little Johnny at soccer practice. Combine multiple trips into one.

4. Lighten your load
Carry only the bare neccessities — don’t haul things in your trunk. “For every extra 250 pounds your engine hauls, the car loses about one mile per gallon in fuel economy.”

5. Reduce drag
About half of your vehicle’s energy is expended overcoming air resistance. (The other half is expended in acceleration.) Reduce your car’s workload — remove anything that might cause drag: luggage racks, bike racks, ski racks, etc.

6. Buy gas on Wednesdays
“Gas prices are statistically the cheapest on Wednesdays, but this is only true over a large number of days. It won’t be true every week.” Gas prices often jump before holidays, too.

7. Don’t go out of your way to save a few pennies on gas
If it’s convenient to shop at a cheaper place, do so. If not, don’t. On a ten-gallon fill-up, saving five cents a gallon only nets you fifty cents.

8. Buy gas during the coolest times of the day
During these times gasoline is densest. Keep in mind: gas pumps measure volumes of gasoline, not densities of fuel concentration. You are charged according to volume of measurement.

9. Use the right octane level for your car
Using premium gasoline in an engine designed to run on regular doesn’t improve performance. Even some vehicles that call for higher octane fuels can run on regular unleaded, though with some loss of performance. (Check your owner’s manual.)

10. Don’t top off your tank
Trust the auto-shutoff. Overfilling can lead to wasted gas.

11. Be sure your gas cap is tight
Improperly seated gas caps allow 147 million gallons of fuel to vaporize every year in the U.S.

12. Drive at a constant moderate speed
Edmunds.com found that the best way to improve fuel efficiency was to accelerate slowly and to brake over a longer distance. Aside from purchasing a new vehicle, this is the single most effective step you can take to reduce your costs. According to fueleconomy.gov as a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas.

13. Use cruise control
If you’re like me, your driving speed tends to fluctuate. Cruise control takes the human element out of the equation, and keeps driving speeds steady. It’s the easy way to drive at a constant moderate pace.

14. Don’t idle
Turn off your engine if you’ll be idling for more than 30 seconds. Starting your vehicle does use a burst of fuel, but not as much as allowing the engine to idle too long.

15. Keep your cool
Most people claim that it makes more sense to use air conditioning on the highway, and to roll down the windows in city traffic. It’s commonly claimed that either method is going to reduce your fuel economy by about 10%. But according to research performed by Consumer Reports, there’s no real difference between driving with the windows down or using the air conditioner.