It is fairly easy to make modern engines, even when housed on motorcycles, and most certainly when mounted in cars, relatively quiet. A lot if not most of the m

It is fairly easy to make modern engines, even when housed on motorcycles, and most certainly when mounted in cars, relatively quiet. A lot if not most of the modern car's engine noise is now made deliberately. Special noise chambers are added to amplify and shape the sound, acoustic isolation is foregone in design, and even in some cases engine noises are actually produced by speakers mounted on the vehicle.