I modified the axle to fit the BCG chassis by trimming the hub a little with a hobby knife. My car took forever to get to top speed, but it was pretty fast. The KIT racers scream with the tall gearing because they are a lot lighter than a BCG, and the motors getting direct power from the battery vs. going through the circuit board first. A clone 2.2 motor that was a dog in a BCG performed much better in the KIT chassis on my son's Hot Wheels track. If someone could figure a way to beef up the motor drive circuitry on the BCG, then the tall gear ratios would work much better.