Part of why I ask was that I DID step on it during my test drive...and nothing happened. No engine roar...nothing. We were on the highway, in light traffic, doing 70. I mentioned it, but we got to talking about something else.
I have a list of specific things to look at for my next (more extensive) test drive, and this is (obviously) one of them.
That particular vehicle has just been driven 300 miles from another location the dealer has, so I wonder if the Max Speed setting had been engaged.
I was fine merging into traffic as we entered the highway.