I now have a problem which is the result of me working in the evening, and not having internet access for several hours. All these answers remained unanswered!
I would have locked it for Iluvatar to name the builder, because he had got so far and I'm sure would have found that answer. Meanwhile, PJ gave me the last remaining answer, and was perfectly entitled to do so.
Although the car was driven by Pierre Flahaut, it was built by Eugene Martin. He campaigned the car in many post-war races, and I was surprised that it had not already been a puzzle.
The simplest thing is to award one point each.
PS The famous "Black Book" names this car as a BMW, so that's what I'm going to call it. I think they were commonly referred to as Frazer Nash by entrants in the early post-war years for political reasons.