Fueleconomy.gov, the official source for EPA fuel economy ratings for automobiles, has compiled a list of the Top 10 Misconceptions about Fuel Economy . The list was developed in response to questions frequently asked by the site’s users and based on input from fueleconomy.gov’s staff of automotive engineers and a panel of experts from auto manufacturers.

Even auto enthusiasts and knowledgeable consumers may find some surprises on the list, because several of the misconceptions generally held true and were considered common knowledge in the not-so-distant past. However, rapid changes in vehicle technologies have made several of these “truths” obsolete or less pervasive.

For example, changing a dirty or clogged air filter could improve your fuel economy significantly in the past, when most vehicles had carbureted engines. However, modern computer-controlled, fuel-injected engines regulate the air-fuel mixture so well that a dirty air filter does not decrease fuel economy—although it can still affect performance.

Also, it was once typical for a vehicle with a manual transmission to get better fuel economy than the same model equipped with an automatic due to the added weight and energy losses associated with the automatic transmission. However, newer automatic transmissions are lighter and more efficient, and it is not uncommon for an automatic-equipped vehicle to achieve fuel economy as good as or better than its manual-equipped counterpart.

Fueleconomy.gov provides an explanation for each of the following Top 10 Misconceptions about Fuel Economy:

1. You have to drive a small car to get good fuel economy.
2. Manual transmissions always get better fuel economy than automatics.
3. It takes more fuel to start a vehicle than it does to let it idle.
4. Vehicles need to warm up before they can be driven.
5. As a vehicle ages, its fuel economy decreases significantly.
6. Replacing your air filter will help your car run more efficiently.
7. Aftermarket additives and devices can dramatically improve your fuel economy.
8. Using premium fuel improves your fuel economy.
9. The EPA fuel economy estimates are a government guarantee on what fuel economy each vehicle will deliver.
10. All vehicles are tested for fuel economy.

Fueleconomy.gov will soon release other Top 10 lists, including the most fuel-efficient vehicles of the past 25 years and the most efficient vehicles as reported by actual drivers.