ezmonee,
You said the sky is the limit for 1 day rentals, which I have come to notice. Say I would book a 1 day rental for my typical car (full size) when I really needed a car for 2 or 3 days. If they upgraded me to something nice (caddy, volvo, etc), what would happen if I called & let them know I'd be returning in 2/3 days or just returned it a few days late?

Thanks