Well my 85' Mayfair is really slow, 0-30 in around 6 seconds lol, but when on country roads I sit at around 50-55. It's very loud at that speed plus I don't like ragging the engine. I don't take it on motorways or A roads as I don't like the idea of meeting even a slight incline! No power whatsoever! My 90' checkmate which has a higher final drive will keep up though and will sit at 50 mph in 3rd gear pretty snug, so I would take this on motorways etc.
My transit van is pretty powerful and would probably do 120 mph, I've tested it up to 100 mph in 6th gear and it was still wanting way more, but I didn't push it (It was an empty motorway when I tested this) I'm not irresponsible and wouldn't cruise any faster than the limit. I'm especially careful in built up areas and alot of the time do a bit less than the limit if I feel I need to. People who get up my a*se just make me even more cocky and I'll just keep getting slower and slower until they get the hint. There's no need to rally about in built up areas, on faster roads they can simply overtake if they like