Did the OP even both to look at the info ZipCar sent? He immediately decides to cry "Fraud and write Consumerist. ZipCar is better off without him.
I'm amazed the OP is justifying his "shady behavior" (a.k.a. THEFT) because of tough times.
That's certainly something to be proud of.
Sheesh, people. What did you expect? They have access to a gold mine of data (your email contact list) and they won't take advantage of it?