Required sound/noise when backing up?

Required sound/noise when backing up?

My wife got a loaner 2012 Lexus hybrid for the day and she noticed the "growling" sound it makes when running in EV mode and backing up. The service advisor made a point of mentioning it to her, saying the car had to emit sound to be 'heard' by people nearby. I know this concept has been discussed before with the Model-S, but anybody "heard" (sorry) more about whether this was a homologation requirement?

Volker.Berlin | June 14, 2012

As you might have guessed, there is an existing thread for this topic:

No definitive information wrt Model S yet.

I'm also curious to learn how Tesla solves it. There may actually be different implementations for different markets, as it will also likely be the case with the brake lights (whether or not they come up upon slowing down by way of regen).

pilotSteve | June 14, 2012

Thanks Volker.Berlin, I should have searched before posting (SBP)! Yes I'm sure this is one of many issues that each jurisdiction issues their own crazy requirements. I'm counting on Tesla to do another great job of threading that needle to make a solution that meets the law but is acceptable to a high end car buyer. We'll see in a week or two, eh?