With a 3 wheeled vehicle, the first things I want to know about are how will it ride and drive, and will it handle differently than a typical car? Will the Cg (center of gravity) be such that it will be stable? Obviously, the location and layout of the battery pack will be key to a good Cg. Will the suspension handle the greater unsprung weight of the wheel motors? The upside of this is it helps the Cg by locating the motors inside the wheels, and it lowers the overall weight by eliminating the gearbox and driveshafts. I think that the wheel motors help improve the aerodynamics; due to the absence of the driveshafts. Round shapes have much higher drag than do airfoil shapes, and a spinning round shape is even higher drag.