I won't tell you the mass, damper or stretch or scale size ratios... because i'm keeping secrets.
180 mph+ on bumpy terrain-- No Problem
Only has 170HP and 1.1x Power Input

Sketch:

Top speed was 192mph but I paused 2 seconds late.
Screenshot:

Note:
My finished creation's top speed will be limited to 140mph (size conversion of 1.7x, that means relative top speed wil be about 2.2x less-- 64mph)