If you put the GoPro inside the car and have the correct back on it, no problems. If you use the water proof back you will hear sweet FA! If you don't have the back with holes with you, just take the seal off the back and it helps a little.
As for video quality, the GoPro is much better than the Contour in every way.
If you want too youtube, pay for an editor. I use Premier Elements.
This is a 1080p clip taken from the back of the car, with the water proof back on.
[/url]This is on the side in the wind, with the audio tweaked a little, with the water proof back on.
http://www.youtube.c...BGONkbnOEY&hd=1
Same position with the Contour
http://www.youtube.c...Pyy6oO0leM&hd=1
I've watched some of that YouTube footage on a 60" 1080p TV and it was better IQ than most of the stuff you see in TV here in Aus.