G.M. ?Officially? Introduces 2011 Chevrolet Volt Amid Controversy
G.M.?s press materials call the Volt ?an electric vehicle with extended range,? though the company has acknowledged all along that this electric vehicle would have a gasoline engine under the hood. And while G.M. has provided more product information than was available in the past, its continued characterization of the car as ?purely electrically driven? glosses over operational details that suggest otherwise.
What G.M. has told the press is that the Volt can cover 25 to 50 miles on electric power alone, depending on the terrain, driving techniques and temperature. A 1.4-liter engine running on premium gasoline turns a generator that can power the electric drive motor and extend the range up to an additional 310 miles before needing to refuel the 9.3-gallon gas tank. The Volt?s electric motor produces 149 horsepower and can accelerate the four-passenger sedan to 60 miles an hour in less than nine seconds. G.M. claims a top speed of 100 miles an hour.
Extensive wind tunnel work has reportedly made Volt the most aerodynamic car Chevrolet has ever produced, with a drag coefficient of 0.28. The vehicle platform is typical of today?s automobiles with a unitized body and frame riding on a MacPherson strut suspension.
So what product feature has G.M. neglected to mention? Simply that when driving in extended range mode at high speeds ? when the battery has run down and the gas engine is powering the generator ? the engine provides some assist by means of a planetary gear set that couples it (G.M says ?indirectly?) to the powertrain.
In terms of vehicle dynamics and performance, that may well be an advantage. In terms of electric-vehicle categorization, it clouds the picture, making the Volt?s engineering layout more like a Toyota Prius, which is a parallel hybrid, than G.M had led journalists to believe.
G.M.?s stance, at least in the materials distributed to the press, is that the Volt?s design is singular: ?The Chevrolet Volt is not a hybrid. It is a one-of-a-kind, all-electrically driven vehicle designed and engineered to operate in all climates.?
That depends on how one defines a hybrid. Logically, any vehicle equipped with both a combustion engine and an electric motor is a hybrid. In keeping with the electric powertrain terminology common to diesel-electric locomotives, the Volt would best be described as a series hybrid.
G.M.?s insistence that the car is fully electric is hard to understand in light of the fact that the gas engine provides motive power under certain conditions.
A G.M. spokesman, Tom Wilkinson, said, ?There is some mechanical drive force at high speed. The engineers wanted to maximize the overall performance and eliminate any potential flat spots in the acceleration curve.?
When asked why G.M. didn?t mention this high-speed gas-engine assist previously, Doug Parks, a global electric vehicle executive for G.M., said that the automaker chose not to publicize this feature to protect the technology during the process of obtaining patents.
In the end, how the vehicle performs in the real world will be much more important than any terminology. But it may be a while before that information is available. Numerous publications are anxious to conduct long-term tests, and some have complained publicly because they?ve been unable to secure cars.
?We simply don?t have enough cars at this time to satisfy the demand,? Mr. Wilkinson said. A two-week press event is under way, and almost every available Volt is being used at that event. What?s more, all of the Volts available for testing are preproduction cars. Production-line vehicles are not yet available.