Hey BT,
How are you my friend? They will fly with a 1,600cc VW Type 1 engine with less than 100hp, to tell you the truth. These "Little Basturds" to quote James Dean, with a WRX engine could likely get it in low earth orbit.
My demontration vehicle will be a standard 160 hp VW Type 4 engine, when we get a few under our sales belt, I'd sell it and move up to a 200 hp T4 or Porsche 914 engine and 5 speed transaxle. Later maybe a Subaru.
Here is the only photo I have showing a Subaru engine being fit to the chassis.
Time will tell, there is so much to do at this moment in time, I'm gonna walk before I run. I want to do this for a long time. Right now a major mistake would be fatal.
You Be Well Dear Friend, Be Well.