Perhaps add a dyno (dynamometer if you want to sound smart) to the game, it doesn't necessarily need to measure your power. It can be used in combination with the already existing dyno UI application, but currently we can only rev our cars to see how much power they make. I think it would be nice to have an actual physical dyno with rollers and everything that we can hook up our cars to. An example below:
The wheel rollers are fine and all, but they don't provide any resistance to the torque and power os it's essentially the same as hanging your car in the air and spinning the tires.