That's a professional film/cinema camera. Costs 5 figures for the body and boring kit lens (average lens for this level of camera) . Definitely check out 60D. Awesome for vids.
5D's are great. But yeah, that audio issue does exist. Only if you updated the firmware, or got the newer ones with the glitchy firmware on it.
5D out of the question, 60D hands down.
If only nikon didn't cap the FPS to 24 or something... :[
I'd just use a DSLR for filming. More choices for lenses. And I could use my cousins 50 million lenses and flashes. Haha.
edit
low aperture short focal length lens. And is why I'd prefer a DSLR for filming than a cam corder. $$$ though
To get that effect you need low aperture lens. Only thing focus has to do with it is making the car sharp. Aperture gives controls the depth of the picture. which is what you're seeing with the blurry background, low apature = shallow depth of field.