British Forces since 2000

[Imp]

With regard to speed 59 kmh seems right. It is commonly said that Warrior IFV's have had problems keeping up with both Challenger and Challenger 2 off road

This is just a case of the game not being able to rate offroad performance vs road I think.
Sure I read more than once the Challenger has very good off road suspension & hence is more capable off road than one might expect.
Same thing I think holds true for the Merkava on the certain terrain it will outperform seemingly faster units.
This will apply to many other vehicles as well not all 4X4 are born equal but it has little impact & is not possible to fix.