A car coming off lease now would probably be a 2000 or maybe a 2001. If you want an 04 or 05 you're going to get a daily rental.
Frankly, as a group I don't think that most rental cars are abused. Although there are always louts with no respect for other's property, most people that would rent a Corolla, Taurus, or Sebring are not looking for a joy ride. As far as maintenance goes, I would think that the average rental car gets it more regularly than the average car. After all, a rental company cannot afford to have cars fail due to lax maintenance. Rental cars are certainly cleaned more often.