Interesting.
Porsche story must have looked promising at the time. Although I feel economy would not have been too fantastic, and that's where the market has now changed. If a manufacturer is look at producing any new engine, it must be one of, if not the most critical requirements.
Rotax...... I'm sure I recognised that name. Thinking about it further, I had a Rotax in a jetski once, the 582 on their website looks to be a direct take from that! I also had a jetski with a Rotax 912, and although it didn't appear the same visually as the GA one, I'm sure it's just dressed up with varying bolt-ons.
A 2.4L, fuel injected, turbocharged diesel, producing 180bhp, at 15L/ph.........that's what I'm thinking of......