Actually, your car starts up when you call anybody. When I'm in a pretty shitty predicament and my car's dead, I hit the phone, and tap X (PS3) as fast as I can, and with Brucie being the first listed on my contacts list, it calls him under "Call". My car starts up, and I'm outta there.
Listen carefully to me. You'll never see another guy like me if you live to be 5000