Here's my theory why some was shot in black and white and some in color.
Maybe some
PR footage was available in color so he threw that in. what the hey! Also the film Rendezvous, which features an unknown car careening through paris (I think he runs at least 15 stoplights) was supposed to have been filmed by his camera car around the same time. That's a lot more exciting than A Man and a Woman. If you watch it, turn it up to full volume
it's available on DVDs though copied so many times it's pretty fuzzy by now.
I think the car is a Dino by the sound but can't tell. It seems to have a
crashbox,unsynchronized gears by the downshifting doubleclutching required.