Hi Cro,
Basically correct. If you have one motor which is 90% efficient and converts 100 kW, the system losses will be the same as four 90% efficient 25 kW motors. However it is likely that the larger motor can have an increased efficiency over the smaller motor. So the 100kW motor might be 93%, which would then favor a single larger motor versus 4 smaller ones.
Also, a single motor may benefit from a reduced mass versus the total mass of four smaller ones. Things like bearings and housings will not be 4 times larger on the single motor. Also, the gear reducers will benefit from economy of scale making one larger one superior to 4 separate units. But offsetting that would be the mechanical power transmission to the wheels, assuming all 4 wheels need to be driven, or even just 2 from a single motor.
From an electromechanical energy conversion efficiency viewpoint, the situation favors a single machine, in my opinion. But packaging, power management (traction), handling (weight distribution), economics, etc. will influence the design decisions.