I've been doing a fair amount of travel lately and typically use Avis for my car rental and have noticed some nice features they have to provide good customer service.

Something they started doing a little while ago is to e-mail a receipt immediately after the car is returned. This is nice if you happen to lose the receipt they give you when you turn the car in.

Yesterday, I again rented from Avis and for some reason they didn't have my car waiting through Avis Preferred. I had to go into the preferred office and they set me up right away (and gave me a car several classes above what I reserved), but what was a very nice touch was that an immediate e-mail was sent to me apologizing for the delay in service. Nice touch!