Ha ha. I always noticed that too and laughed. Although did you ever notice the Rolls? It's actually in pretty rough shape. Look along the side I think maybe at the scene where they're ditching Tony's car (can't remember for sure). It looks like it has a lot of dents or maybe crappy body work done to it.
I'm going to have to look for those dents. It's pretty obvious that Jarvis was letting his hobby cause him to live beyond his means.