GM and Daimler-Chrysler and BMW to launch hybrids

Last weekend, three major automakers announced details of the hybrid system they developed cooperatively. GM had previously announced its hybrid strategy, although details on the two-mode hybrid system were mostly conceptual. At last weekend's announcement, the companies went into more detail, describing the two-mode system as using a two-mode electronic continuously variable transmission combined with four fixed-gear ratios. (In contrast, Toyota's Synergy hybrid system uses a single-mode continuously variable transmission.) The two-mode system is designed to optimize fuel efficiency at low and high speeds, with the four fixed-gear ratios either allowing for greater performance flexibility or adding needless complexity. The three automakers embarked on the joint research project to save development costs, but we have yet to see if the system will be a distillation of the brightest ideas or a case of too many cooks spoiling the stew. The initial incarnation of the system is designed to work in front-engine, rear- and all-wheel-drive cars, an arrangement appropriate to the automakers involved. The first cars with the system will most likely be the 2008 model-year Tahoe and Yukon.