Well they are both blistering fast....which can you get parts for the easiest? If you can get parts for both....hmmm. I really like both but have only ran the T-Tec. Is the Fusion shaft drive? The belt drive system of the 4-Tec is the biggest thing I don't like about it. Next thing....the Fusion will drink a ton more gas than the 4-Tec. They are almost the same speed but the Traxxas can be ran in a little smaller area since the car in smaller. Still they are both big parking lot machines.