[elhigh]

+1 on lengthening the car and laying the driver down. As Freebeard pointed out that will improve the fineness ratio and allow you, with the lower helmet position, to also lower the roll bar and get it out of the wind. Incorporating a fairing into the downwind portion of the rollbar would be good, esp. if you can also have a windshield that will aerodynamically couple to the upwind side of the roll bar. Things could get very sleek at that point.

Your suspension is an aerodynamic mess. If you can fair the fore-and-aft elements together, you have only half as many wakes to contend with.

+1 on adding smoothie discs to the wheels.

Virtually any body at all is going to perform better than your bare tube chassis. If you're breaking 60kmh already, get ready for a big surprise when you add some body panels.

It sounded to me like you were describing how you had added weight to the wheels to make them coast longer. If you're running with weight in the wheels, get it out. Move the weight into the body itself, as low and as centrally located as possible. Lighter wheels accelerate better and give a much smoother ride, and keeping the weight low will allow the car to take turns better.