http://www.instamotor.com is in the same space. Looking at both of their sites, Instamotors seems more inviting and explains things better.

There's no question that the space is ripe for disruption, but the problem with both of these services are:

1) How does the consumer know you'll actually get a better price for them? The only way to know for sure is to list it yourself and see how you would do. There is a conflict of interest here, because these sites would rather have a quick sale than take a long time negotiating an extra few hundred dollars.

2) I don't necessarily feel comfortable giving strangers access to my car so they can give other strangers test drives.