OK so my belief is that a fully tracked vehicle can move cross-country faster than a wheeled vehicle because a wheeled vehicle has to go around a ditch, a rock, a soft spot. A tracked vehicle can go straight over it. The detour can be quite long. A tracked vehicle can cross a ditch at speed a wheeled vehicle has to virtually stop. A tracked vehicle can manage a steeper slope. A wheeled vehicle has to be careful (slow) when travelling cross country because it is much easier to hang it than a tracked vehicle.
Because cross country speed is fixed at either half or one third of road speed a game wheeled vehicle nearly always has a better cross country speed than a tracked vehicle because it has a higher road speed.
The tracked Opel Maultier should have a better cross-country speed than a 2 wheel drive Opel truck but in game they are the same.
M3 Halftrack should have a better cross country speed than the M3 wheeled scout car, but it is actually less.
There are any number of similar examples.
I think a tracked vehicle's cross country speed should always be higher than that of a wheeled vehicle unless the tracked vehicle is very slow.
I think in reality all vehicles actually travel quite slowly cross-country, because they have to pick out a path and avoid obstacles. And because when the gears are working in the cross-country low range then acceleration is much slower. In game the range of cross country speeds is I think too large. Britain's Matilda moves along cross-country at 9 kph, Humber LRC II can travel cross-country at 39 kph while jeep can belt along cross-country at 51 kph. At 51 kph a ditch or rock will have the vehicle airbourne, and broken. A vehicle built to have good cross country ability will usually have low road speed. A vehicle built to travel on roads will have a low cross country speed. The opposite is true in the game because the higher the road speed the higher the cross country speed, within a class.
At this site you can calculate Jeeps cross country speed.
http://www.public.asu.edu/~grover/willys/speed.html
With 28 inch tyres at 4000 rpm with low selected a Jeep has a cross country speed of 40 kph, game has 50 kph However 40 kph is cross country speed at maximum engine revolutions which isn't appropriate for cross country driving. In the rough we are looking for maximum torque, that is achieved at 2000 rpm, this gives a cross country speed of 20 kph. So the game cross country speed for Jeep is more than twice what it should be.
Jeep details are available at this site
https://www.automobile-catalog.com/auta_details1.php
It seems to me there is a very simple way to make more vehicle cross-country speeds similar. Flattening out cross-country speeds reflects a generally more careful approach to cross-country travel. I think different type vehicle's cross-country speeds are generally the same because they all have to drive carefully. One way of making all vehicle cross country speeds similar across classes would be to change the fractions used to calculate cross country speed,
from
Moveclass 2(Wheeled)ccspeed = 1/3 road speed
Moveclass 3(A/T Wheeled)ccspeed = 1/2 road speed
Moveclass 4(Track)ccspeed = 1/2 road speed
to
Moveclass 2(Wheeled)ccspeed = 1/4 road speed
Moveclass 3(A/T Wheeled)ccspeed = 1/3 road speed
Moveclass 4(Track)ccspeed = 1/2 road speed
So the fast road vehicles cross-country speed drops a lot more than before but only to about the speed of a tracked vehicle anyway, or if we are lucky less.
This 1/4, 1/3, 1/2 format also makes I think an important distiction between wheeled and tracked vehicles. Amongst other differences a tracked vehicle can always take a much straighter path cross country than wheeled. And so can take a much shorter path to an objective, ie travel further.
In game the speed of travel matches the duration of a turn, The ROF however does not, for example if the game turns are 3 minutes each then a large AT gun with ROF of 10 rpm should get about 30 shots per turn but it actually only gets 3. This problem applies to every weapon in the game. Lowering cross-country speeds is the same as giving the AT gun slightly more shots per turn as it takes more turns for its target to traverse a given distance. So lower cross-country speeds make the game not only I think a bit more realistic but also slightly improve the ROF/Movement mismatch
I would mention here that fixing the ROF and Speeds mismatch can be achieved by rescaling the game to 25m hexes. This would be straightforward to do by simply doubling ranges.
As well as lowering the fastest cross country speeds, lowering the maximum road speed would also have the same effect of slightly improving the mismatch between movement and ROF. It is unlikely any vehicle actually ever travels at maximum speed for any length of time. Negotiating corners, poor visibility, wet road, icy road, heavy loads, towing, recommended speeds, various obstacles, the vehicle is worn, the road is worn, you don't want the engine to blow up, the driver is sensible and so on.
I think it would be suitable to make game maximum speed about 4/5ths of current maximum speed. This is easy to do, wherever the code reads maximum speed from the vehicles data multiply it by 4/5 and pass on the new lower value in place of maximum speed. You could put in place a lower cap so maximum speeds less than say 21 kph, still use full maximum speed.
You could then choose to use the capped 4/5th maximum speed to calculate a slightly lower cross-country speed.
Motor cycles get a road speed 90 kph this gives them a cross country speed of 45 kph this is clearly a suicidal speed to ride across country. I would move motorcycles and the early 6 wheeled armoured cars into 1/4 movement class 2.
I don't think Infantry really moves any faster on road than on clear, surely they can run just as fast on clear as on road. I would make infantry movement the same on road as it is on clear, 3 hexes.
I seem to remember regular Japanese Infantry used to have a movement factor of 7 that got dropped at some point. I would be overjoyed to see that reinstated.
Polish units 548 and 549 are interesting in that they illustrate a missing element in the game, the Horse artillery, these were able to keep up with regular cavalry. So I guess some armies might get a light load, speed 12, limber. See
https://en.wikipedia.org/wiki/Horse_artillery
Thanks for your time