This sounds almost sinister, but it started out quite innocent
As far as I remember, the first car to pump sound into the cockpit was a Mustang a few years ago. It wasn't artificial sound, but a tube that amplified the actual sound. It was done because of customer complaints about the lack of engine sound!
The engine in my Chevy HHR sounds absolutely awful. It makes a groaning sound that isn't pleasant at all. I wouldn't mind an artificial sound of some sort.