I have the VW 1.9TDI for my REX and it will be coupled to another Leaf motor to directly charge the batteries. I just have to get a speed increaser set up so I can run the TDI at less than 2000 rpm (within its best torque range) and the generator at perhaps 6000 RPM. It is a bit of an experiment of course. I am very curious how Damien controls all this. It is helpful that he has a complete unit so that wheel does not need to be re-invented.