[Al Skierkiewicz]

Andrew,
If you ever saw the current demand of a tank tread turning on carpet, you wouldn't even think of using it. You can't beat the traction moving forward or back but you will eat a battery trying to turn in a single match. Those that work have some method of raising the track so only a small portion is in contact during turns. Even four wheel and six wheel drives suffer from high current demands unless they employ some method of raising some wheels in turns or use omni wheels on some of the wheels (i.e. front wheels).
If you were to tell me that in driving your robot draws less then forty amps total current but you wonder why your battery runs dead in less than two minutes, I would be able to tell you are using tank drive without ever having seen your robot.