Wait, what? So Cadillac is going to give you a $50 AmEx gift card just for the grueling labor of... test-driving one of their luxury cars? It's a rough life, you know?
Okay, they're going to collect your personal information and probably run a credit check on you while you're out tootling around in their Escalade. And yes, you are giving them permission to contact you at the number you provide (although it is very easy to accidentally enter the wrong phone number when you're typing quickly). And there might be an element of time-share captive-audience endurance while you wait impatiently for them to finish their pitch and cough up your gift card. BUT STILL.
I recommend not showering, and wearing your oldest, holiest, paint-stainedest clothes, maybe mention that you're coming down with swine flu. The worse you look, the quicker they'll want to give you your gift card and get you out of their showroom!