While this is best answered by someone doing location sound every day, my $.02 is road noise is rarely an issue. After all it’s expected. With windows up most cars are quiet enough. Sound guys I’ve hired have used a Schoeps mk41 capsule with a special cable (whose #s I don’t remember) mounting it to the rear mirror support. Two mic are used if there are two people in the scene. Although I’ve never tried it, I’ve heard of people using boundary effect mics, too. For me, the “sound” of a car interior (oddly hollow-ish) always bothers me so there’s tweaking to do in post.
John
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