a fully dressed powerstroke is probably around the 1200lb range, pretty heavy for a such a light car. Your best bet would be a VW TDI. They are not huge on power, but with injectors and computer mods, you might be around the 250hp range. The only other option would be a 4bt Cummins. Once again not real big on power. They are mostly bread trucks and small industrial equipment that use these. The is very little performance upgrades for them. Navistar/ford have been discussing, a 4 cyl PSD to put in rangers, and a 6 cyl PSD to put in 1/2 tons. The way the diesel craze is going I would bet you might see them in the next few years.