To Fatelogic:
Well... the reason you cannot accelerate anymore isnt due to earth's gravity not being infinite, there can be infinite acceleration at any weight of gravity - what limits acceleration is the force of friction from the air. Given a hypothetical situation where there was an infinitely long vacuum tube, the acceleration would accelerate non-stop. The gravity would then determine how fast the acceleration would be.
I'm pretty sure I'm right, but there's always a chance I could be wrong.