There's YC-backed Carwoo - http://carwoo.com http://carwoo.com. I believe they are quite experienced guys and have built relationships with lots of US dealers.

There's YC-backed Carwoo - http://carwoo.com http://carwoo.com. I believe they are quite experienced guys and have built relationships with lots of US dealers. Even though any individual won't use such a service often, each sale is quite big in absolute terms (compared to other verticals I'm considering) and a lot of people buy cars. So, it is a big market but not one I'm currently thinking of, mainly because I'm only looking at stuff you'd actually order online.