Efficiency
50% peak.
Other free piston designs have theoretical efficiencies approaching 59%.
Direct combustion to hydraulic pressure.
You will see 60% in the next 10 years.
Valentin has been working on this for a long time, paid $75k for a full page ad in the New York Times about 15 years ago.
The INNAS BMW conversion doubled the vehicles mileage overall, and that was a diesel BMW that was fairly efficient to begin with.
The lean burn Insight was supposed to approach 48%.
Recharging the accumulator allows peak engine efficiency always.
Posted links on previous threads.
regards
Mech