Fluid power hybrid

[manojjonam10]

Hydraulic and pneumatic hybrid vehicles use an engine to charge a pressure accumulator to drive the wheels via hydraulic or pneumatic (i.e. compressed air) drive units. The energy recovery rate is higher and therefore the system is more efficient than battery charged hybrids, demonstrating a 60% to 70% increase in energy economy in EPA testing .

[ex-EV1 driver]

Do you have any examples of vehicles with pneumatic accumulators?
I'm skeptical of your numbers because of the heat generated in pneumatic compression. Hydraulic transmissions have been used for years for heavy equipment but I don't exactly know why they haven't been used for automobiles.