My choice would definitely be the black and white picture. It looks more retro. I wouldn't crop much on this picture, so we can see where the Volkswagen 1600 is heading. Maybe cut some from the top and the right side of the photo.
I have never been a sucker for either B/W or old cars, so I like the color version much better. It is a very nice red-green-blue color triad. It has no colors that complicate the picture, so it doesn't really gain anything by losing them. On the opposite, the car stands out much better as red against green, which I think is lost in the B/W version.