Hydraulic drives are used on everything from hightech tanks and jets to simple lawnmowers.
While their 170mpg claim will need to be proven, the idea of hydralic fluid drives already has great potential to reduce energy consumption, drive line wear and friction.
My favorite idea is like 'Valentin' to build a 'drop in drive' or 'add on' system to upgrade current gas hog fleets.
I would prefer a turbine system that could run on nearly any source, eliminating nearly 30% of fuel used in our world lost during refining and distribution. But that is sooo 1960's ;-)
"According to all accounts this went from zero to 150mph in 4 seconds before becoming airborne and sliding out of control."[Turbonique fan site]