Well, honestly, I'm glad it seems to have worked, but I don't know how much more 'mileage' there would be in it. As tight as credit has been, it seems like this probably represents the cream of the borrowing crop deciding to stop sitting on their hands and dump the oldest car in the family for a bonus. Continuing the program would likely run into problems with prospective customers not having high enough FICO scores to get the main loan, and the pool of the credit-worthy who had just been sitting it out is probably running low already - after all, they would have been the ones in a position to respond quickly, so most of those who would be interested in that group probably already bit. Easier credit from lenders would make extension of the program workable, but that is pretty much out of the Government's hands and God willing will remain so.
The deal doesn't make any sense for me personally, mileage is a tertiary concern behind avoiding new debt and ruggedness/reliability...a paid-off smaller SUV or small/medium pick-up of 10+ years age is the vehicle best-suited to my own needs.