I realize in general the main goal is to get through a track as fast as possible.

But that said, if I wanted to simulate certain vehicle characteristics, is it possible to control vehicle top speed and acceleration rate in a track with scripts?

It is possible to modify acceleration, gravity and the amount of control you have over the vehicle (the amount of steering which is possible) with a script while it is not possible to directly control the vehicle's top speed as far as I'm aware.
There even was a MTC based around the usage of modified physics settings a while ago: https://tm.mania-exchange.com/threads/3254/mtc-september-2016-bring-your-own-physics-update?page=1