Prototype 2 died after .5 miles. The motor drivers overheated.  The motor encoders slipped out of alignment.  The manual steering proved difficult.

A nearly complete redesign of prototype 2 yielded the 1st prototype to go 6.4 miles.  

The chassis was widened 20mm.  The steering section was redesigned a 3rd time. 

To cool the motor drivers, the L6234's were soldered upside down & bolted on the angle aluminum.  This entailed soldering 22 flying leads to breakout boards, but it worked.
There was a long drawn attempt to hack an ESC to be a directly controlled H-bridge, but a stock ESC doesn't have enough serial port bandwidth to be updated at the required 16khz.  

The traction module was redesigned for modularity.

The motor encoder was redesigned to use 1 magnet & 2 hall effect sensors.

The motor was made more modular, but it has a long way to go.

With no payload, over hills & bumps, with minimal stops, power consumption was a whopping 175mAh/mile. It could go over 20 miles without a payload, on a single battery. It could also go 10 miles on a much lighter battery.  The low power consumption was manely from the hard tires & very little contact patch. Less benefit was from being direct drive, lions believe.

The mane limitation was now the paw controller. The controls need to be spaced out 10mm in every direction & it needs to be bigger.