I'd highly suggest getting an external microphone. Here's an example (all in one video) of me driving around in my 2002 Civic with the external mic, then removing it so you can hear the internal mic. This is ALL with the windows up. For a new video in my Z, the plan (once it quits raining here in Texas) is to use a splitter (since it is all in mono audio anyway) and run one mic to the engine bay (to hear turbo, wastegate, and BOV), and the other stay inside, while the camera is mounted to the outside. We'll see how this works. Any videos I've taken with the camera mounted to the outside just end up with a ton of wind noise.
And for reference, here's a vid from my RB26 Z in action a few weeks ago all on the internal mic..
Z's: 1990 TTZ RB26DETT now running! 636 RWHP/504 FT/lb @24psi @ 200' ALT Nov. 2011 (retuned from original Dyno) 505 RWHP/483 FT/lb @18psi @ 380' ALT Oct. 2008 457 RWHP/441 FT/lb @18psi @ 5800' ALT Nov. 2007 436 RWHP/433 FT/lb @17psi @ 5300' ALT June 2006
