It's nice that the manufacturer is listening, and that legislation might be avoided. But it would get smacked down in legislation unless they change the verbiage to include all cars when silent, or out of tolerance on a db or frequency.
Wouldn't it be interesting if they standardized the sounds? i.e. if they all had a middle c component of a certain amplitude. If you put the effort into having perfect pitch, you could tell how fast the vehicle was approaching from the dopplar shift, and you could judge the distance by the intensity.
hmm, an arduino "chime" that activates with the kill switch might be a fun project
here is the easy cheezy chime code:
http://www.arduino.cc/cgi-bin/yabb2/...num=1228475606