Hybrid Car Review

Over at GCC, they point out a study on hybrid cars and the trend to heavier, more powerful hybrids is eroding the technologies fuel consumption benefit.

I have to disagree with that conclusion. There is no trend. As one commenter pointed out, the Prius and Insight were the only two vehicles at one point. They weren't designed for everyday driving for all kinds of drivers, but to maximize fuel economy to prove the concept.

As other, more real-world Hybrid Electric Vehicles (HEV) reach market which are based on vehicles which had internal combustion engines (ICE) engines beforehand they are going to be bigger with more safety features and more power. Besides which, some of the new hybrid vehicles have been designed with size, power or luxury in mind, not fuel economy. In other words, the hybrid SUVs, Honda Accord, and Lexus hybrids came along. So, given the small sample size, those cars have just as much weight as the Prius.

The Prius, on the other hand, has improved on fuel economy despite getting bigger. And the next generation Prius is supposed to get even better fuel economy as the hybrid system gets simpler and loses weight. At the same time, the Prius makes up half of all hybrid sales.

So, the marketplace is not trending toward the bigger, the more powerful (see the Honda Accord sales, for instance) or the more luxurious which erodes the impact of fuel economy. Since the market is being dominated by the Prius, and the Prius is getting better fuel economy while getting bigger, the conclusion being drawn is misleading.

This study just points out the obvious. The new hybrid cars on the road are bigger than the old ones (i.e. the Prius and Insight) and as such, are getting poorer fuel economy. The technology, however, still gives those new hybrids better fuel economy than their counterparts. Even when they are designed for more power, that extra power is gained at less fuel cost.

The Study: "How hybrid-electric vehicles are different from conventional vehicles: the effect of weight and power on fuel consumption"; C Reynolds and M Kandlikar; Environ. Res. Lett. 2 (January–March 2007) 014003 doi:10.1088/1748-9326/2/1/014003