Probably already know that one of EcoModder's own has done a Porsche diesel conversion....
Not a kit car though - real, classic Porsche.
moTthediesel's car:
From:
2010 Green Grand Prix: Saturday May 8, Watkins Glen, NY -pics/results posted
Good for ~70 mpg (US) in competition driving (hilly rural route, some city sections, moderate speeds of ~40-45 mph average over the entire course).