I've often thought this should apply to motorcycles too. Motorcycle helmets would have speakers installed inside, wirelessly connected to the bike so that it produces realistic motorcycle sound effects when you operate the throttle.

This way, motorcycle enthusiasts could have all of their "loud pipe" thrills while riding a clean, silent electric motorcycle and not disturbing their neighbors!

For even more realism, vibrators could be installed in the seat to mimic a combustion engine's "vroom".