I think you didn´t understood Flippy correct. With the engine not the total number of vehicles is important, but the number of DIFFERENT vehicles. For every different static, vehicle, weapon, whatever the PC needs to load the new model and texture. That eats performance and makes the map unstable, when you add too many different things. Atm Mareth and El Ala are hard on that limit, so just removing some Crusaders/Shermans wouldn´t fit it, as you have to completly remove a whole vehicletype.