DO units drive faster on the motorway?

Quote from Gooochy

I was looking at one of my FOs and they were flooring it on the M20 but when they got off they slowed down so do they go faster on the motorway if so that is super convient as I always have atleast 1 unit on the M20
I also tried this on the M2 and it seemed to work.

I know that I'm in america and things are slightly changed but I have noticed that in town they seems to drive slower than they do on the motor way/free way, how ever in some rural parts they seems to be slightly bugged on small farm roads ETC.