I test drove an early
I test drove an early prototype 3 years ago in the South of France at MDI's HQ and found the whole concept interesting. It won't overtake general mass production cars any time soon, or even ever but it has a niche market. Airports already use them, mostly Amsterdam's Schipholl and Paris' Roissy. Where the drivetrain makes sense is with short, predetermined range runs, basically fleets. The greatest asset is that its exhaust is pure cold air. Think about the saving for ice cream trucks. The only problem with it is that air compression hasn't changed in over 100 years and once a new more efficient way has been found, this will make sense for small commute.
The prototype I drove felt like an 125 to 250cc scooter, in as far as sound and vibration. MDI also truly has a revolutionary manufacturing concept by creating small assembly lines that can be built quickly anywhere thus avoiding shelf life in one central repository. Negre, the guy behind the air engine is an interesting fellow and has good ideas. I'm glad it's finding a practical application with fleets.