GM Plugs In

GM's announcement that it intends to build plug-in hybrid cars can be interpreted in several ways. Clearly, some will see this as mere marketing hype from a company that has so far fielded only "mild hybrids" and one true hybrid that is still in its first model year. On the other hand, it may be a sign that GM understands the degree to which it has yielded the technological lead to Toyota and Honda, which have second-generation hybrids on the road and third-generation hybrids on the drawing boards. Given the growing importance of the Chinese market to GM's profitability, and in light of China's new, tougher fuel economy standards, the company that brought us the Hummer might just be starting to get it, concerning fuel economy.

When journalists mention plug-in hybrids, which supplement a hybrid car's recovery and electrical storage of braking energy with an overnight recharging capability, they usually focus on the batteries. These must be more robust than for a regular hybrid, and some engineers argue that they should employ different chemistry, as well, given the very different charge/drain cycling involved in all-electric driving. The other part of this equation, of course, is the motors. In order to deliver acceptable performance (see yesterday's posting) a plug-in must have a fully parallel drivetrain, powerful enough to accelerate the car safely without constantly resorting to the gasoline engine. That redundancy, along with the heavier-duty batteries and electronics, substantially increases the cost premium over "conventional hybrids"--a term that would have been an oxymoron a few years ago.

It's a long way from the Chevy Silverado Hybrid, with its bigger battery and starter motor that provide instant on/instant off at traffic lights--contributing minimally to powering the car while in motion--to a full plug-in hybrid car or SUV. If these mild hybrids and the new Saturn constituted GM's only experience in this area, the road ahead would be very steep, indeed. However, despite all the grief GM has taken for killing it, including allegations of a conspiracy, the EV-1 battery car of the 1990s established GM's bona fides in the field of electric propulsion. The legendary enthusiasm of those who leased that model while it was available represents a strong vote of confidence in GM's ability to produce a practical and attractive plug-in hybrid in a few years, provided GM can remain solvent long enough to deliver on this promise.