Recently on the mutant future forum over at goblinoid games forums have been posting vehicle stats that were in line with the vehicles posted in Mutant Future. The top speeds for vehicles is posted in mph. Which isn't the handiest figure for a game where pulse pounding action is resolved in 10 second rounds.
There are 60 rounds per 10 minute turn and as such there are 360 rounds per hour. A mile is 5280 feet long. Divide 5280 by 360 and we get the handy figure of 14.667 ft ; not the handiest measure.
To make the math all a little cleaner later we could crank this up to 5mph increments. That's 73.35 feet and as such for the sake of still easier math I recommend bring this down to a tactical speed of 70ft a round per 5 mph of true speed.
Sounds great but that is damned fast and not easily factored into the rest of the movement rules.
As per the rules an unencumbered humanoid runs 120' a round, that's a real speed of 8.18 mph. Not Olympic greatness in sprinting but certainly enough running speed for long distance hauls.
Vehicle speeds could always be assumed to be "running" speeds of course but a vehicle moving even 5 mph by my math above will be out racing an unencumbered humanoid. For the sake of game reality turning down the per round movement of vehicles could be a safe way to go.
I'm gonna recommend 50ft per 5mph of speed so bottom speed vehicles can occasionally be caught up with by people on mounts. It also works out to handy 10' per mph in a round.
Yes it bends reality but it works for a game.
A vehicle going 50 mph will be covering 500 a round. Much slower then reality but easy to keep track of if we don't worry too much that a round is 10 seconds long. It also lets us pretend that running characters are actually approaching running speeds.
So for quick and dirty math / easy conversions 10 feet a round for each mph, when dealing with vehicles.
Now someone just has to figure out how you keep track of adventurers moving 30' a round compared to a jet roaring along at 560 mph.