The engine noise you hear on the fine roads of the United States of America are often artificially enhanced, according to the Washington Post.

Fake engine noise has become one of the auto industry’s dirty little secrets, the report says. Drivers want better gas mileage, but also the sound of a powerful car. Volkswagen uses something called a “Soundaktor.” Porsche has a “Sound Symposer.”

Can you tell the difference? Here are sounds of a real Ford F150, and the “enhanced” version. Which is which? Go down to our comments to see the answer.