Stomp on the gas in a new Ford Mustang or F-150 and you’ll hear a meaty, throaty rumble — the same style roar that Americans have associated with auto power and performance for decades.

It’s a sham. The engine growl in some of America’s best-selling cars and trucks is actually a finely tuned bit of lip-syncing, boosted through special pipes or digitally faked altogether…

Fake engine noise has become one of the auto industry’s dirty little secrets, with automakers from BMW to Volkswagen turning to a sound-boosting bag of tricks. Without them, today’s more fuel-efficient engines would sound far quieter and, automakers worry, seemingly less powerful, potentially pushing buyers away.