When President Bush rolls down Pennsylvania Avenue this Thursday he will be doing so in a car that hasn't been seen in public yet. GM has given the presidential limo the front and rear clips of the soon-to-be-unveiled Cadillac DTS, the Deville replacement. Obviously the roofline and the middle of the car are all special-built for the president.The Deville was last car in Caddy's lineup to get the redo and is still FWD and on the same chassis.