I'm guessing that mine doesn't have one as it's dead quiet...just as I like it!
Did you actually hack into the car's recording sample to add your own?...I'd like something similar to the whoosh sound we hear when we first start the car, only a longer loop of course...if it's gotta make noise, at least make it something that makes people wonder what it is?I am currently working on making a better version right now, just got audio out tonight.