To perform a simulation, you can't use combination of mph, kmh etc. All units must be in one system.
Imperial units are useless for any kind of calculations/simulations.
Nope. MSTS uses metric units internally too. Everywhere.The Engine/Wagon reference document issued with MSTS defined MaxVelocity as a default value of 100 mph not km/h that implied that the "standard" for Velocity was mph.
Mph is mentioned in a reference document, because it's "american" game after all.
So, MSTS converts these mph, hp etc to metric units too.