The Chevrolet Volt, which made its world debut at the Detroit auto show in January 2007, may prove to be the most significant concept car to be introduced this century – so far, at least.
Unlike most concept cars, it’s not the Volt’s styling that defines it – in fact, its styling is quite derivative. It is the car’s engineering that sets it apart.
The Volt employs an electric-drive architecture that General Motors calls E-Flex. In the words of GM vice-chair Bob Lutz, it promises to be a “game changer,” and in this case that claim may be more than just hyperbole.
The other thing making the Volt significant is the fact that its technology was destined from the beginning for production – in the near term, not 20 years out. Within months of the concept’s debut, GM announced that a production version would be built, with a target introduction date of calendar year 2010.
In purist technical terms, the Volt is a hybrid, employing both an internal combustion engine and an electric motor. GM prefers not to call it such, however, for it is unlike any other hybrid currently available.
Without getting too bogged down in technical exotica, it is a series hybrid, while those currently on the market are parallel or series-parallel hybrids.
Unlike the latter, Volt has no mechanical connection between its gas engine and its wheels. It uses a gasoline or diesel engine solely to drive a generator, which in turn provides power to an electric drive motor (or motors) or to recharge a battery pack.
The Volt and its derivatives can also be plugged into a common household electric outlet to recharge the on-board batteries, which will take about 6.5 hours.
According to GM, the vehicle can then be driven up to 64 km on electric power alone before needing recharging, either through the use of its gas engine (which is considerably smaller and more fuel-efficient than would be used in a non-hybrid vehicle) or by being plugged in again.
That may not seem like much distance, but more than 70 per cent of American drivers travel less than 64 km round-trip in their daily commutes, GM says. (Comparable Canadian figures are not available.) For those drivers, if they recharged the Volt each night at their homes, “they would never have to buy a drop of gasoline,” Lutz says.
It is because of that pure electric drive capability that GM prefers to call the Volt an electric vehicle with a range extender (the gas engine) rather than a hybrid.
What sets the Volt apart from other attempts at practical electric vehicles is that, if the driver needs to drive further than the range the batteries can provide, he or she won’t be stranded. In fact, with the gas engine powering the car’s on-board generator, the range can be extended to several hundred kilometres on a single tank of fuel.
If the daily commute is 100 km rather than 64 km or less, Lutz says, the fuel consumption of the Volt would be in the range of 1.6 L/100 km – just over one-third that of a typical current hybrid. For those who still think the old way, that is 180 miles per Imperial gallon.
During periods of constant engine operation, to sustain battery charge, fuel consumption is estimated to be 4.7 L/100 km.
While the E-Flex concept sounds simple in principle, there remains one big hurdle to be overcome. Lithium-ion batteries are seen as a necessity for commercialization of plug-in electric vehicles of any type.
They offer increased power and energy density (capacity per unit of size and weight) compared to the nickel-metal-hydride batteries currently used in most hybrids.
Lithium-ion technology is already widely used in cellphones, laptop computers and power tools, but there are significant challenges in scaling up the technology for use in automotive applications, where they must be connected in series to provide an output of up to 350 volts.
Chief among those challenges is thermal management – a problem that has resulted recently in fires and corresponding recalls in some laptop and cellphone applications.
While semi-hand-built lithium-ion battery packs have been successfully adapted to low-volume automotive production, such as in the Tesla roadster, the technology is not yet at the stage of commercial feasibility for mass production, given all the technical and liability constraints applicable to the automotive environment.
That was the big challenge GM had to overcome if its goal of 2010 is to be realized. There was some risk involved in the venture when the Volt was revealed, Lutz conceded, but he estimated the potential for failure to be just 10 per cent.
“We wouldn’t undertake a project like this if we weren’t pretty confident we could succeed,” he said.
While it was a tall order, that confidence appears to be well placed. Real-world testing of pre-production test mules is well underway and GM is said to be on the verge of announcing a production contract with one of two battery suppliers: Compact Power Inc., a subsidiary of Korea’s LG Chem Ltd., and German-based Continental Automotive Systems, in conjunction with A123 Systems Inc. of Watertown, Mass.
GM has been proceeding with production engineering and development of the Volt and the broader E-Flex architecture in parallel with its battery development initiatives so one won’t hold up the other. A plant in Michigan has been allocated for Volt production, and in a recent interview Larry Burns, GM’s vice-president in charge of research and development, said a late-2010 target for Volt production still looks feasible.
Beyond just the promise of the Volt, the E-Flex architecture is capable of adapting to multiple electrical power sources, ultimately including fuel cells, with common electric-drive systems.
It won’t happen overnight, it will probably take several forms, and it is unlikely to totally replace the fossil-fuelled internal combustion engine for decades to come. But the future of the automobile appears almost certainly to be electric – one way or another.
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