MP412-C 3161 lbs 592 hp
F1 2513 lbs 627 hp

The weight difference is too big even tough the MP4 is a slightly bigger car.
Maybe the F1s double central tunnels (it has 3 seats) provide stiffness with low weight?

Maybe you get what you pay?
F1 was about the more expensive car back then while the MP4 is a "bargain" at about $400k