Friday, July 24, 2009

Q&A: Doubling Prius' Gas Mileage

We frequently get questions about different aspects of LHI. I will be posting some of them here in the hopes that readers will find the info interesting or helpful.

Q. I don’t know what to say when somebody makes impossible claims about their new product. This design seems similar to a Prius, except that the hydraulic system will store much less energy than the battery in an electric hybrid. How could this possibly double the mileage of the Prius? The hydraulic hybrid system is well-known. It is fine for delivery trucks, but offers few benefits for a general-purpose car.

A. The hydraulic system has the benefit of storing energy at a much faster rate than the electric hybrid. It is true that the electric hybrid system can store a larger amount of energy, but that energy is also not free because of the fact that the electric system cannot recover the full amount of energy in even a normal driving cycle stop. The Prius often runs the gas engine in order to maintain energy levels in the batteries. In terms of energy density the two systems may be comparable but in terms of storage rate and efficiency the hydraulic system has an advantage. This coupled with the fact that a turbo diesel engine is about twice as efficient as the gasoline engine in the prius and the body design of LH4 improves the already excellent drag characteristics of the Prius with a lighter chasis and body substantiates our claim of doubling the efficiency of the Prius.

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