He's trying to combat high moment of inertia by centralizing mass. I used this concept when designing a putter last year (except I wanted high MOI so that the face rotated slower).

The concept of MOI can be understood by looking at a ice skater. Stick your arms straight out (with weight away from your center of rotation), and the skater spins slowly. Bring your arms in towards your body, and the skater spins faster.

So by centralizing mass, the car will rotate quicker in corners (in theory)- it's not just about weight distribution to the tires.

Your design looks similar to the new Serpent mid motor, though the steering servo is in a more traditional position.