Fuel efficiency myths, Like all drivers, you want to save gas and do what’s right for your car. But along with the tried-and-true advice, there are some well-intentioned—if off-the-mark—tips that can lead you astray. Below are several common myths about fuel use and gas mileage, and the real stories behind them. (Learn more about fuel economy and how to save at the pump.)
A dirty air filter drops gas mileage
Our tests show that driving with a dirty air filter no longer has an impact on fuel economy, as it did with older engines. That's because modern engines use computers to precisely control the air/fuel ratio, depending on the amount of air coming in through the filter.
Reducing airflow causes the engine to automatically reduce the amount of fuel being used. Fuel economy didn't change in the family sedan we tested, but it accelerated much more slowly with a dirty filter.
