This is something that I've toyed around with a CANbus hacker called CANiTM (which is open source hardware) -- while I have Nationwide Insurance, I did call up Progressive and ask for a snapshot; they sent one to my house, and I was able to save me driving around a farm at reasonable speeds.

I then tweaked the CAN bus parameters a bit -- making the VIN number match the VIN of my current vehicle, and replaying that a few times during the trip so that it would seem like I'm a very patient, slow driver, who drives less than 5 miles a day at 8:30 and at 5:15, monday through Friday, and then sent it back to Progressive at the end of my 30 day trial.

Progressive quoted me an insanely small number for my auto insurance -- probably around $22/month -- which is about half of what Nationwide charges me for the same insurance.

It's my understanding that Progressive now is collecting GPS data with their snapshot tool, so I'm not sure that the same attack/replay would work for their system.