“The potential for grid-connected vehicles to decimate our demand for liquid hydrocarbon fuels should be clear. Freed from the psychological barriers which hinder widespread market acceptance of pure battery electric vehicles, plug-in hybrids with an all-electric capability of just [30] kilometres would slash liquid fuel consumption, since such a high proportion of journeys undertaken are well within this range.”

"Plugged In: The End of the Oil Age” by WWF
(Dr. G. Kendall, 2008)

Comparison to Toyota Prius Engine
The Toyota Prius 1.8L 2ZR-FXE engine delivers 30kW @ 3,000 rpm; 102Nm; 8.62 Bar; BSFC 220g/kWh (37.2% efficient) and 73kW @ 5,200 rpm peak. It uses the Atkinson cycle with an effective compression ratio of 9.5:1 and an expansion ratio of 1:13 due to delayed valve intake closing. The crankshaft is off-centre in relation to the cylinder so that it has passed the vertical when the piston is at top-dead-centre (TDC). The loss of low-speed torque is compensated for by the electric motor. The engine weighs 97 kg. This engine can be regarded as one of the most advanced, efficient gasoline engines in the world; yet the Libralato engine is predicted to be about 39% efficient, 4.8% more efficient (relative) with less than half the mass.

	The Libralato engine has a new geometry and thermodynamic cycle compared to a 4 stroke engine, but it shares a key feature with the Toyota Prius engine. The Libralato engine has an Atkinson-like cycle since the physical volume of the expansion chamber (approx 1300cc for 50kW) is greater than the physical volume of the compression chamber (approx 920cc for 50kW). This gives rise to a compression ratio of about 10:1 and an expansion ratio of about 1:14.2. The figure on the left indicates the extra work which can be extracted from the cycle, to the right of the dotted line.
The figures below is an indicative illustration of a BSFC engine map for the Libralato engine.