I had a co worker that was an M-1 Tank Driver and he spilled the beans on the top speed of the M-1 in hard packed desert floor, it was not 45mph. If its NOT a top secret mention the real speed.
Top Speed for an M-1? As fast as the driver dares go!
I can personally relate the experience of driving on the highways near Ft. Huachuca, AZ, at 55MPH, and an M1A1 on the frontage road pacing me. But judging from how banged about the tank was, it was a rough ride for the crew.