I was wrong. My GM Financial rep said in the case of a GM Financial Single Pay lease that GMF does not pro-rate the lease. They pay you back the difference between what your insurance company deemed it was worth and what the residual value was. So in that regard a single pay lease can be risky. You could buy a 50K car with a 50% residual, cut the 25K ish check to the dealership only to total it the next day and have your insurance company say it's only worth 40K. You would get back the difference between 40K and the residual of 25K, which means you pay 25K and only get back 15K.

That's a pretty big drawback to a single pay lease in my mind.