Running layout and for fun had my 20 car MTH N&W 611 freight follow behind a no cars MTH diesel engine. Both were run at 20sMPH and both kept same distance apart. When I increased the 611 speed by 1 or 2 mph, it slowly began to close space. Reducing 611 speed made it slowly fall back.
So experiment proves nothing other than how well MTH cruise control works when engine pulling a load and not, compared to another one, and how well the MPH are matched between disparate engines. Was expecting one or other to slowly gain or lose space after 10 or more circuits.
Close enough for government work. Be interesting how well an MTH and Lionel play in the sandbox as far as speed settings.