http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880002196_1988002196.pdf

I don't have time to read it all right now, but it looks extremely interesting, especially considering it uses hydrogen as the working fluid.

This may seem to go o/t......but. What you referenced was 1985 attempts at doing something with Stirling engines, not necessarily for cars, but to prove the engine itself, which they do use on the space shuttles today. Take a look at what the government has done recently with not only hydrogen and Stirling, but combined with solar. I am presently working on my own personal version for my home.

http://www.sandia.gov/news/resources/releases/2008/solargrid.html