Hybrids are hot. People have heard about them. They know a hybrid is some kind of miracle powertrain that gives 50 mpg in the Toyota Prius
. And it's great for the environment.
But the Prius is a pretty small car. What would really be great is a hybrid pickup or SUV. Sure, it might not get as good gas mileage as that little Toyota, but, heck, even if it only got 30 miles to the gallon, that'd still be pretty good.
Actually, that would be great-sort of like the all-pie diet where you lose five pounds a week. Unfortunately, neither is reality.
What is reality, however, is that GM has introduced hybrid versions of its Chevy Silverado and GMC Sierra pickups. The trucks began trickling into commercial fleets a few months ago, but now they're ready for retail sale, in volumes limited only by demand-and by geography. For the '05 model year, the trucks are offered in six states: California, Oregon, Washington, Alaska, Nevada, and Florida. Next year all 50 states will get them.
This is not, however, some 30-mpg miracle truck. That's because being a hybrid is not an all-or-nothing proposition-there are degrees of hybrid-ness. The Silverado/Sierra hybrid is what's called a "mild hybrid," and as such, it offers mild benefits.
All hybrids use electric power in addition to a conventional internal-combustion engine. The extent to which the electric power helps out determines the degree of the "hybridness" and the extent to which fuel economy increases and emissions are lowered.
The much-ballyhooed Prius, for example, is a so-called "full hybrid," meaning it's capable of running solely on battery power-shutting off its gasoline engine-at idle and when driving at low speeds (up to 30 mph or so). The batteries don't just take over for the engine, they can also help it out, which allows the Prius to get away with a smaller-than-usual gasoline engine for a car of its size. Because its electric motor does so much work, and because of its smaller-than-standard engine, the Prius achieves headline-making mpg and ultra-clean exhaust emissions.
On a slightly less fantastical scale are the Honda Insight and Civic Hybrids. Honda's battery-powered electric motor can help out its gasoline engine, allowing for a smaller, more economical engine; and the engine can shut down when the car is stopped. But Honda's electric motor can't power the car during low-speed driving, so the mpg gain and emissions decrease is less dramatic.
The Silverado/Sierra hybrid uses electric power even less frequently. Its gasoline engine can shut down when the car is stopped (actually, when it's braking to a stop, below 13 mph or so) and-that's it. The batteries (three 14-volt units plus the standard 12-volt) cannot power the truck at low speeds. Nor do they help out the gasoline engine, which therefore can't be any smaller. It's the same 5.3-liter V-8 GM pickup buyers know and love. Because of the limited nature of this hybrid system, the benefits are mild: roughly 2 mpg in city driving and 1 mpg during the EPA's highway cycle.
Although the GM hybrid system does not produce great gains, neither does it demand great compromises. Because the 5.3-liter V-8 is the same as that in non-hybrid pickups, its power and torque outputs are the same (295 horsepower, 325 pound-feet of torque). Acceleration, towing, and payload are undiminished. The extra hybrid gear takes up very little space-the biggest component, the three extra batteries, is under the rear seat. One interesting feature of the hybrid trucks are its four, 120-volt 20-amp AC power outlets in the cargo bed and the rear seat; but the engine must be running in order to use them.
We drove a Sierra 4x4 with the hybrid system. All hybrid-equipped Silverados and Sierras are 1500-series extended cabs. Two- or four-wheel drive is available. All controls are the same as any other GM big pickup, but there are subtle differences in the way the hybrid drives. First off, the engine fires up instantly. Because it uses a much more powerful starter motor, you don't hear it spin for a second before the engine starts. Hold your foot on the brake and shift into Drive, and the engine shuts off. This is a non-event, however, because the electric motor continues to run all the accessories (including the air-conditioning).
Take you foot off the brake and give it some gas and the engine instantly restarts. If you do this quickly, a sensitive driver may notice a bit of hesitation before acceleration starts, and also might sometimes hear a slight clunk from the driveline when moving off from a stop. In all other driving situations-low speed acceleration, coasting, freeway driving, whatever-the hybrid powertrain is indistinguishable from any other 5.3-liter V-8.
In all, driving the hybrid-powered Sierra 1500 4x4 extended cab is little different from driving any other Sierra 1500 4x4 extended-cab. That's both its strength and its weakness. There's really nothing weird to get used to in driving and no sacrifices in capability, but the payoff is minor as well. The cost is $2500.
For those hoping for more, GM will introduce a more radical hybrid on its Tahoe and Yukon for 2007. As for the all-pie miracle diet, that's probably further off.