Using an external mic is really the only way to get good engine sound while driving. This example had a small mic sticking out the bottom of the passenger door at the forward position facing aft. The camera was mounted on the rollbar. No wind noise but you can hear a little tire-on-pavement sound. I used a Zoom H4 portable digital recorder and synched up later in post production. The new Heros have an external mic input I understand, so you wouldn't need a separate recorder now.