The Ultimate Economical Driving Quiz

If you don't maintain your car properly you might be reducing its mileage by as much as 25 percent.

There was a time when spark plugs had to be changed every 10,000 miles. These days they last at least 30,000 miles.

Many people recommend changing your car's oil every 3,000 miles. That might actually be overkill, but it won't hurt your car nearly as much as engine sludge will.

The manufacturer's handbook for your car will usually include a recommendation about the type of oil you should use.

Air intake is an essential element of combustion. The less air your car intakes the harder it has to work, which burns more fuel.

Reduced power means reduced gas mileage, so replace your filters regularly. It could save you as much as 23 cents per gallon.

By replacing your spark plugs you increase your car's overall efficiency. It can save you as much as 75 cents per gallon!

Your tire pressure will naturally decrease by about one psi per month. Check it at least that often.

For every one hundred pounds you carry in your car you lose one mile per gallon. Emptying out your trunk and removing the roof rack can really help.

Driving at high speeds greatly reduces fuel efficiency. Once you go over 60 miles per hour you reduce your mileage by 25 percent.

Running the air conditioning system reduces your car's horsepower by about 15. Roll down your windows to help save gas.

Economical use of fuel is not only a financial issue, it's a social one. Reduction of fuel consumption is one sure way to help the environment.

An astounding four in 10 cars on the road have at least one underinflated tire! That's not only bad for fuel economy, it's extremely dangerous.

Cold air is denser than warm air. For every 10 degrees Fahrenheit that the air cools, the pressure in your tires, which is measured in pounds per square inch (psi), will decrease by one point.

While off-road tires may look really cool, they don't get the kind of mileage that all-season tires do.

According to the Environmental Protection Agency (EPA), a tune up can improve fuel efficiency by as much as 10 percent.

As far as car maintenance goes, nothing will reduce your gas mileage as much as a faulty oxygen sensor -- up to 40 percent.

The EPA has inspected over 100 items that claim to significantly improve gas mileage, and found only half a dozen that had a statistically significant result. If it sounds like a gimmick it very likely is.

Stop-and-go traffic reduces mileage. That's why the sales sticker has a lower estimated mileage rate for city driving than for highway driving. Avoid traffic to improve mileage.

Rather than weigh down the car with a heavy liquid, wait till the gas tank is down to one quarter of a tank before stopping for gas.