AnnaS: I did rent a Jaguar from Budget in Boston when they had their promotion and all went well. As an Amex Platinum Card holder I have elite-level memberships comped in all four major car-rental companies.

Generally I find Avis to have the best combination of cheap rates and good service, especially at Las Vegas... I show up there and my car is already running, waiting for me! The exception to Avis is LAX, where the service is consistently bad and I never get the free double-upgrade I'm supposed to get.

Unfortunately I'm addicted to Neverlost, so I've been renting more from Hertz, which always costs the most.