This is Spottswoode's Lamborghini Diablo Limousine used on the Brooklyn Bridge after Baxter hits the 'Valmorphanize' button. This particular model was used during the overhead shot when you see the wings pop out from the bottom of the Limo. It's approximately 14 inches long with an 11 inch wingspan.

Here's the bottom with the wings retracted. They appear to be model jet wings slightly modified and would have had a string attached to the little eye-screw on one of the gears. The string ran through the little tube at the back of the Limo and would have been pulled to make the wings extend. Fiberglass body with wood front wheels (and plastic wings).

Screenshots in action:
(No headlights are installed in the prop, that effect was added after filming.)