"The Beijing (China) Bus Company will soon begin a large-scale test of heavy-duty hydraulic hybrid systems, deploying the technology on 50 buses that it will use in daily operations. Successful results could spur broader use of the hybrid systems within a year. Instead of the battery pack and electric generator/motor used in electric hybrids, a hybrid hydraulic system uses an accumulator (which stores energy as highly compressed nitrogen gas) and one or more hydraulic pump/motors." http://www.hybridcars.com/blogs/hyview/hydraulics-beijing
As much fun as it would be to experience a wreck in an electric hybrid, picture this: A hydraulic hybrid is hoppin right along and all the sudden something bad is about to happen. The driver cranks on the brakes which fully charges the hydraulic system (to what? 5000psi) just as impact is made, you only have to damage the 'lines' or somehow breach the canister(s). At those pressures, what kind of explosion do you get from something like this. Probably about as much fun as crashing an electric one and wondering exactly how things are going with the current in the car (lines, frame, wreckage).. Ford put this kind of system in a F250 a couple years ago. They had it up in the 30's for mpg...
