Steering is too hard, crashing often occurs

Watch your replay slowly to spot where the vehicle buckles right before it flips/crashes.  I hold a record time of 2.90 seconds on the S-Bend, it just hasn't shown up in the listings because of what seems like a bug.  This is part of the entire challenge of the game.  Also try a wider wheelbase as you've got the robot quite high there and as a result the centre of gravity is above the wheels.

As the other comment says, it's not the game fault, it's your design's fault. Use a wider vehicle base or go slower.