Yes....and it doesn't change. None of them ever will.
Extremely unlikely, unless you drive around in Track Mode.
You can yourself, with a bit of work and an assistant. You need to get a platform with a slight indentation (top of a bottle should work) that you secure firmly and level (using a level), and a ball to set in the indention. Get up to speed as assistant holds the ball in place, assistant takes hand off the ball and you release the accelerator. Do that in both vehicles, probably a few times. You might have to play with ball/indentation size to get the correct sensitivity so it is easy to see the difference.
Best way to "release", to take foot-lift bias out, is likely to use CC with the Bolt and turn it off. With the Tesla use CC and disengage it.
Presto, a McGyver brand g-meter.