“There Is No Three-Day Right to Cancel…
If we could impart just one piece of information, it would be to remind you that there is no three-day right to cancel a car contract. Once you sign on the dotted line, the car is yours. The Minnesota Attorney General’s Office hears from many consumers every Monday morning who assume they can still return the car they bought Friday night. They can’t. But they learn this lesson the hard way. So, don’t be one of our remorseful Monday morning callers—remember: when you buy a car, it’s yours!”
Quote taken from Minneosta Attorney Gernal’s Office Web Site. It can be found at the bottom of this web page.  link