While only seen in flashback at the start of Speed Racer, the Mach 4 is nonetheless an important car in the movie. Driven by a young Rex Racer, the proto-T-180 has a design esthetic that fits in perfectly with the Mach lineage. It is the car Rex uses to teach Speed how to drive, and the ghostly image of which Speed races against in the opening scenes at Thunderhead.
Except for a few lovingly rendered closeups, most of the time the car is seen only as a ghostly blur (Mattel even produced a Hot Wheels version with a translucent red plastic). It is clear though that it has a distinctly retro look, complete with visible bolts and seams — as you can see from this rendering by Phiyen Nguyen. 
SPEED RALLY
Cinematic games for miniatures
SPEED RALLY 