Bloomberg is reporting that General Motors stopped work on the Cadillac Converj, a sleek electric-drive coupe, to focus on cheaper plug-in hybrids for its luxury brand. The report is based on comments from two GM executives who asked not to be identified because the details aren’t public.
The decision, if verified by GM, represents an acknowledgement of the high cost of producing plug-in hybrids that run for long distances without using any gasoline—rather than the type of plug-in hybrids that can use smaller and therefore less expensive battery packs. The Cadillac Converj was intended to follow the design of the Chevy Volt—referred to as an extended-range electric vehicle or plug-in series hybrid—which runs up to 40 miles before the gas engine is used to maintain the vehicle’s range.
“The future lies in plug-in hybrids with smaller electric range,” Eric Noble, president of CarLab, an Orange, California-based automotive consultant, told Bloomberg. Dropping the Converj is “a tacit admission from GM that they over-batteried the Volt.”
Right-Sizing Plug-in Hybrid Batteries
The three major categories of electric-drive vehicles are conventional hybrids, plug-in hybrids, and pure electric cars. Conventional hybrids, like the Toyota Prius, will continue to use relatively small battery packs—while pure electric cars require much larger batteries in order to deliver approximately 100 miles of range between charges.
The decision to drop the Cadillac Converj underscores the debate about the optimal size of the battery pack for a plug-in hybrid, which offers many of the benefits of an electric car—such as using energy pulled from the electric grid or rooftop solar panels—while providing a driving range which matches or exceeds a gas-powered vehicles.
Cost is a major factor. GM has insisted that 40 miles of range, without using a single drop of gasoline, is critical. However, Toyota plans to offer a plug-in version of the Prius with about 13 miles of all-electric range, and Ford’s Escape Plug-in Hybrid will provide around 30 electric miles—with both vehicles expected to put the internal combustion engine to some use throughout the drive cycle, if it means overall greater efficiency. This approach is sometimes called a “blended” strategy. GM’s own plug-in hybrid SUV in the works is reportedly aiming for approximately 10 miles of electric-only range.
One of the key questions that auto engineers hope to answer with plug-in hybrid pilot programs is how small they can make the battery pack—to reduce cost—while daily driving remains gas-free.
According to executives quoted on the Bloomberg story, the extra cost of pushing the Cadillac Converj’s electric-only range even to 20 miles would be $30,000. Pat Morrissey, a GM spokesman, declined to comment on the future of the Converj.