The small rover wheel had a power of 0.0002, which apparently is less than the minimum possible - the rover only moved on 3x physics warp. Increased the power consumption. It may be possible to increase it less than I have increased it.
Adjusted power of small rover wheel so that it consumes enough energy to work without physics warping.
Merge pull request #23 from BryceSchroeder/master

Rover wheel energy consumption