Buddy: Originally thought they had a fantastic concept and opportunity (and really still do think there is a market for what they were promising).
In doing DD, every answer turned up about three new questions. One was just how many of that Mark 5 engine had they shipped to customers.
The answer turned out to be zero, but it took a lot of reading to discover that. All the photos of shiny engines, boats with engines, truck frame with engine, lawn mower, and land speed record cars turned out to be non-functional mock-ups of engines. All the performance claims were made up. All the talk of customers and applications and orders coming in was just hot air.
It could be Harry and Frankie originally had good intentions, but they've known for years their engines just don't work and they have no idea how to make them work. Meanwhile they've been telling investors during these years the engines will be in production in the next six months, knowing fully well a first class miracle will be needed for that to come true.