I don't think you would get bad sport for that. If each of us is driving his own vehicle you'll be the one who destroyed it for the game's purpose. Not absolutely sure, but makes sense. If I crash into someone or someone crashes into me and then my car falls in a river or from the docks the game shouldn't distinguish it.One suggestion would be not to use personal cars - as have the feeling people could get labelled bad sports fairly easily if you knock a couple of personal cars off the top!!
Each person should just steal an 'average car' and, once they have lost the cops, meet at the skyscraper.