There is no return policy because this is all one big scam.
Go back to Craigslist and check the page that you have to go through to get to the car ads... see the scam warnings? If you click on the examples, they will probably look like the auto-reply you received via email.
They are start the same... you get an email from someone with a sob story as to why the car is SO cheap (WAY WAY under book value): they're divorcing, in the military, moving overseas, death in the family, etc. They want to use some official-sounding escrow service (like "Google Checkout" or "Yahoo! Purchase Protection", neither exist in this capacity) and want the money wired. There is also always an excuse for not speaking via phone. Finally, they entice you with a "return period" if you don't like the car... shipped free, of course.
There is no magic deal, this is a HUGE scam... these folks are overseas, and once the money is wired, it's gone. There is no retrieving it.
Don't fall for it.