Would a motor be unsprung weight if not connected to the suspension? By reading that wiki, it looks like unsprung weight is basically wheels, tires, suspension directly supporting those things. The parent comment seems to be referring to putting two engines in the front, and two in the trunk, not necessarily above the tires (if that's even possible?).

The way I discovered one of my cars needed new shock absorbers was driving down a very steep hill toward the stop light crossing a busy intersection. The road was super bumpy and one of my tires kept losing contact with the road. I managed to stop but it was a much closer thing then I was comfortable with. Scheduled an appointment at the auto shop very shortly after that.

Going down an incline or around a curve without all four tires on the ground is terrifying.