Grit Tech uses mQNP, but is not yet complete. you can test out a pre-release of the mod here:
http://forum.shrapnelgames.com/newup...1041370616.zip
or read about the mod here:
http://www.shrapnelgames.com/cgi-bin...;f=23;t=001946
I am still working on balancing the engines, I am thinking of making them indirectly porportional to vehicle mass, instead of directly porportional.