Ok so I knew your could drive a prius in GT4 and see the wonders of HSD in action. But what I don't know is that there was a version in Japan called GT4 prius edition which allowed the player to drive around a track for not best track time but the best tank! Man if this would expand into a real life simulation, then we can practice hypermiling in the comfort of our own home

then I bet 100 mpg would be a joke by then, one can dream.

http://ps2.ign.com/articles/451/451383p1.html