It's just maths, but con't ask me to explain. I think it goes back to the old V=+AT formular at school...........?
Unless you have gots lots of gears (like the F1 car did at the pod) I have never seen a car run fast ET's without a good 60 foot time. And I was still quicker in the Sox because my 60 foot times were better. The same applied when Tig got beaten by the scooby.
Unless you have an overdrive facility it is a trade off. The paradox is that if you do not accelerate quickly then you will never attain a top speed, if you gear too low to get acceleration then you will not be able to achieve a high speed because you run out of revs.
This is why Gear selection, tyre height and the motor's ability to PULL the required revs at the end of the track are so important.