Hm.
So Drive gives a 1.1x modifier
The land loss calc is:
$loss = mt_rand(1, ceil(($enemy[$building_type] * 0.07 + 2) * $modifier));
So if the enemy had 10,000 acres all in huts an attack has a chance to take between 1 and 772 acres. The Drive modifier is applied to the max possible, not the amount taken (...I'd make an argument for it being applied after the calc, but I didn't write it).
Basically the same as QMT, RNJesus was not on your side.