Terry, of course, drives the Batmobile (http://www.batmobilehistory.com/beyond-batmobile.jpg) (Batjet? Whatever, the flying car that can go up to Mach 3). And whatever car Bruce needs him to drive when he has to be a chauffeur for the old man.

For his own vehicle, though, I see him as more of a biker then a car-driver. I know dick at all about motorcycles, but he'd probably ride something sleek and sporty. Possibly something vintage (by his standards, of course).