FYI, UA and AA have terminated their programs. AFAIK, the only program to earn miles anymore is www.dealermiles.com. Other programs are for financing, or are like the Hertz program special offer.

And how many times have you frequent travelers been in a car in a strange town and BOOM, you hit a speed bump, curb, shopping cart, whatever, and you say, "Oh, well, glad it's a rental." Now, do you really want to go buy a used rental car from Hertz?