Car ads generally suck, but there was one for the VW Jetta a few years back that was just hilarious. There's a couple riding along in their car, and the husband tells his wife he thinks they just accidentally returned a certain "home video" they made. Then it cuts to the rental place and you hear the two of them giggling as the customers and employees all stare at one of the TVs mounted to the ceiling.
There's a link
here.