2011 Chevrolet Volt First Drive and Review
DRIVING DOWN THE ROAD
WITH CAREY RUSS
2011 Chevrolet Volt; So is it a hybrid or not? Who cares? It works and won't leaf you stranded by the side of the road…
The Chevrolet Volt is one of the most interesting, and controversial, cars available today. Demand far exceeds the limited supply, so I'm not expecting one in the local press fleet any time soon. But I did have the opportunity to get a good feel for the car last week, with time on uncrowded back roads and in city and freeway traffic.
The Volt is a real, and completely functional, car. It's quiet, comfortable, and quick enough for any real-world driving situation. With the electric motor's strong low-end torque and an excellent chassis tuning, it's an enjoyable car to drive. It feels like, and is equipped like, a regular car. There are no discrete gears, so no shifting, much like an internal-combustion or hybrid car with a continuously-variable transmission (CVT).
Unlike a hybrid, the Volt's internal combustion engine (gasoline in this case) runs only to charge the battery pack (*, see below) and so does not necessarily come on when the car is running and shut off when stopped. The result is an unparalleled degree of smoothness and quiet in electric mode. The 1.4-liter four-cylinder engine is small enough, and balanced and mounted and insulated well enough, to be only minimally-perceptible when running.
What it is and what it isn't: GM calls the Volt an extended-range electric vehicle. It's not a hybrid, as the gasoline engine is never the sole power to the (front) drive wheels. The "Voltec Electric Drive System" is much more complex than a simple battery-electric vehicle, and, like a series-parallel full hybrid, has multiple drive modes.
There are two electric motors, one a traction motor and the other a motor-generator, the gasoline engine, a planetary gearset to blend power inputs, and three clutches to control power inputs, plus a 16kWh battery pack in the Volt's power system. Drive modes are:
Single-Motor EV: When the battery pack is charged, the primary traction motor is the sole source of propulsion at low speeds and hard acceleration. (remember: an electric motor produces maximum torque as soon as it begins to turn, and torque drops of at higher revs.) The planetary ring gear is locked, and the motor-generator is decoupled from both the engine and the gearset. The traction motor uses up to 111kW (149 hp) of power and delivers 273 lb-ft of torque, equivalent to that of a 3.0 to 4.0-liter gasoline engine. This means very good low-speed acceleration, just what is needed for most city and country-road driving. Or most driving, period.
Two-Motor EV: As speed increases, the ring gear is unlocked and coupled to the motor-generator, allowing both motors to work in tandem for improved efficiency and giving up to two extra miles of pure EV operation at highway speeds.
Single-Motor Extended Range: When the battery pack reaches its minimum charge -- 30% in normal operation or 45% in "Mountain Mode" -- the gasoline engine starts and is coupled to the motor-generator via a clutch. At lower speeds and under hard acceleration, electricity so generated, plus reserve in the batteries, provides drive power comes from the traction motor alone, with the ring gear locked, similarly to single-motor EV mode but with additional electricity from the motor-generator via an inverter. NOTE THAT unlike a hybrid, which uses its internal combustion engine to fully charge its battery pack, the Volt's engine only maintains minimum charge in the battery pack, with full charge dependent on plugging into an external source of electricity.
*Two-Motor Extended Range: This is similar to the two-motor EV mode, but additionally the engine is turned on and powers the motor-generator via a clutch. The motor-generator is also connected to the ring gear, via clutch. Connect the clutches and… yes, some torque from the gasoline engine sometimes makes it through the motor-generator to the ring gear and from there to the wheels. Still, even at this point, the motor-generator and battery pack provide electricity to the main traction motor, and the traction motor is the main source of propulsion. The traction motor is always the main source of propulsive torque. Blending torque from the traction motor and motor-generator/engine combination increases efficiency at highway speeds by 10 to 15% than use of the traction motor alone.
So yes, the Volt's powertrain is complex, and it's not a pure electric vehicle. Which should be a complete non-issue, and has a major advantage over a pure EV: when the battery pack's charge level reaches minimum in an EV, you're standing at the side of the road waiting for a tow truck. When the same thing happens in a Volt, you may not even notice.
The Volt's battery pack is fully charged by being plugged into an external source of electricity. No complex, expensive charging station is necessary; it can be recharged in 10 to 12 hours connected to a regular 120-volt outlet. A 240-volt recharger is available, and that cuts charge time to four hours or so. Yes, charging time can vary…
Although not apparent from outside the car -- or from the passenger cabin -- the battery pack and other drivetrain components have their own climate-control systems to keep them at optimum operating temperatures. Batteries don't work well in cold temperatures -- I once had an interesting conversation with a fellow journalist from Detroit who claimed to have gotten to the end of his driveway in a fully-charged lead-acid battery EV1 in the winter. EV1 fans in Los Angeles may not have had that problem… and Volt owners never will. (And yes, the gasoline engine is liquid-cooled, too.)
Efficiency is designed into all aspects of the Volt. Aerodynamics were a key consideration. The climate control and audio systems were designed and built to minimize their energy consumption, and low rolling-resistance tires further increase the distance the Volt can go on a a kilowatt or gallon of regular unleaded. Structurally, it is of standard steel unibody construction, on a platform related to the similar-looking Chevy Cruze.
Even with efficiency considerations, passenger comfort is not compromised. All of the comforts and conveniences expected in a car in the $30-45,000 price range are standard or available, and interior (and exterior) materials and fit and finish are first-rate. I didn't have time to make a thorough investigation of the interior, suffice to say no sacrifice necessary. There is even good trunk space. This is a completely useable daily-driver car, not an experimental proof-of-concept vehicle.
Safety equipment? Everything you'd expect. Next topic…
The driving experience: It's a car. There is nothing unusual about the Volt driving experience. Get in, press the start button, and go. Okay, on a full charge, the engine doesn't come on when the start button is pressed -- just as often happens in a hybrid. Low-speed acceleration is very strong, and there is no noticeable gear shifting. Power modes change seamlessly. There are driver-controllable modes as well. Sport remaps throttle response for quicker acceleration, and Mountain keeps a higher reserve in the battery pack, for assistance climbing long, steep grades.
My morning drive was on scenic, twisting California Highway One south of Carmel. The Volt had been charged that morning, and still had enough charge when I got to drive to be operating fully electrically. The mileage indicator said "250+", the maximum that can be indicated. Later in the day I got into a different example at the event base in Seaside, north of Monterey, for a short drive through city streets and on to the freeway in evening traffic. It was in extended-range mode by then, and indicated 46mpg. No complaint there, either, as that's comparable to a Prius. Other testers have noted that more time in extended-range mode results in lower mileage, as in low to mid 30s. Which is comparable to my experience with similarly-sized Toyota Camry, Ford Fusion, and Nissan Altima hybrids. As with any car, and even more so with hybrids, your driving style and the terrain and conditions on your route determine mileage. So your mileage may vary, as they say…
Conclusions? It's not the super-revolutionary incredible new transportation technology that some early hype may have implied, but the Chevrolet Volt is an impressive piece of engineering that is also a real car. No compromises necessary, and recharging merely requires a regular 120-volt power outlet. It's the next step in "hybrid" drivetrain technology, and is a generation or two advanced over any competitors. It works, and well. Expect to see more of this technology in future GM vehicles.SPECIFICATIONS
2011 Chevrolet Volt
Base Price $ 40,280 - 7500 fed tax credit = 32,780 Price As Tested $ n/a Engine Type DOHC i6-valve inline 4-cylinder with continuously-variable cam phasing Engine Size 1.4 liters / 85 cu. in. Horsepower 84 @ 4800 rpm Traction motor Horsepower 149 (111 kW) Torque 273 lb-ft Torque (lb-ft) 273 Transmission planetary gearset Wheelbase / Length 105.7 in. / 177.1 in. Curb Weight 3755 lbs. Pounds Per Horsepower 25.2 Fuel Capacity 9.3 gal. Fuel Requirement 87 octane unleaded regular gasoline Tires Goodyear Fuel Max Brakes, front/rear vented disc all around, ABS and regenerative braking standard Suspension, front/rear independent MacPherson strut / torsion beam axle Drivetrain front engine and motors, front-wheel drive PERFORMANCE EPA Fuel Economy - miles per gallon city / highway / observed ymmv - see text 0 to 60 mph 9.2 sec OPTIONS AND CHARGES n/a
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