As far as weight removal once you remove all the other seats you might as well ditch all the sound insulation, air bags(at least for the other passengers), sun roof, AC, heater, and a million other things you don't need in a race car because nobody is going to make it a daily driver with only one seat. Anyone know how many demons were sold with only one seat? I bet very few and they will be the collectible ones in 30 years.

I am not causing global warming, I am just trying to hold off a impending Ice Age!