Wednesday, November 10, 2004

Is a "Mild Hybrid" an Oxymoron?
Much of the buzz about hybrid cars has come from one hot model, the Toyota Prius, now in its second, improved version and selling like hotcakes. Ford is introducing a hybrid Escape (small SUV), and Honda has several hybrid models, but no one can say these cars are really mass market yet. The introduction of a "mild hybrid" pickup truck could change that, but is it worth the extra cost and complexity?

Environmentalists and those concerned about energy security get excited about hybrids because of their potential to improve fuel economy dramatically. In the case of the Prius, this improvement amounts to at least 50% better fuel economy than a comparable Camry (admittedly a somewhat bigger car.) But with sales of 50,000 Priuses per year, how much impact can you have on the fuel economy of a 200 million car fleet?

This is where the "mild hybrid" comes in. Unlike the full hybrids, such as the Prius, it does not have a separate electric drivetrain. Rather, it saves up some of the energy of braking in a 42 Volt battery and uses it to run accessories and to enable shutting off the engine at stoplights and restarting it instantly when the driver depresses the accelerator. The net result, at least in the case of the Chevrolet Silverado hybrid pickup, is a gas savings of about 10%, on a model that has sold about 500,000 units per year (in non-hybrid form), at a cost premium about half that of the true hybrids.

The question then is whether the "mild hybrid" technology, which is simpler and less expensive than full hybridization, and can thus enter the vehicle fleet more quickly and in much larger numbers than the Prius, is a useful adjunct to full hybrids or will undermine the whole concept by disappointing owners with its modest benefits. Only consumers can answer, as they determine whether modest fuel savings plus the cachet of a hybrid are worth the extra cost. GM won't be the only carmaker watching the outcome.

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