http://www.carmax.com/ does that in the US, they have a business model of no haggling and give some gaurantees on the cars they sell.
In California, CarMax and other dealers don’t need to register a purchased vehicle in the company name. So even with her release of liability, the DMV considered the former owner to the registered owner of the ticketed vehicle.
http://consumerist.com/2013/04/19/woman-hit-with-traffic-tic...
I am pretty confident that California law is advanced enough to handle the case of selling a car to someone. Carmax doesn't have anything new in that realm.