See, I was going to argue that, too, but forgot... except, my argument was predicated on the fact that BT allows for both ICE and Fusion engines to be placed into tanks, dependant on how one builds their tank.  As for being required to put a lot more into movement, that's not true, either.  It's easier for a machine to roll than it is to walk.  Tanks can have a constant gearing ratio that allows for them to keep moving at the same speed, like a car, while 'Mechs would have an alternating gearing ratio for balance and switching between legs.  'Mechs definitely would have to put more into it, hence the reason all 'Mechs, except in stupid Dark Age, have Fusion plants in them.

lol ok ok... geez people