Tuneman -- you're absolutely right about not always wanting to drive larger. I guess my peeve with Hertz is that they will pull the C -> YC thing even when you're using a "one class upgrade" coupon or something similar. With National it's not an issue, because you pick your car at most locations -- so if the upgrades on the Exec aisle are gigantic SUVs, you can just go to the midsize aisle.

Really what I'd love is a rental agency with Hertz's car fleet and National's aisle system.