Get a tripod or some other form of camera stabilization. Don't rely on in-camera stabilization.
Close ups of the engine are always good while showing a dyno. As is showing the back wheels rolling and the computer screen after the run. Keep in mind that you need to keep the dyno screen on camera for a long enough duration for people to actually be able to read it. Show not only horsepower and torque, but boost and A/F too.
Roll credits faster and keep the under five seconds.
No music during the actual car scenes. Music only during the credits.
For autocross or other racing scenes get a shotgun microphone so that the audience can hear the car. Do any narration in post. Don't talk over the car.