General Motors is a little bit behind in the hybrid race. But they’re starting to catch up. Although more advanced hybrid models from GM are on the way over the next two years, for now the company is offering a “mild hybrid” version of its big Chevy Silverado and GMC Sierra pickups, keeping the same V-8 powertrain but claiming a fuel economy improvement of 10 to 13 percent.
With other hybrids up ’til now, an electric motor system is configured somewhere within the drivetrain, and it aids the engine during acceleration, improving fuel economy — especially from a standing stop and during low-speed heavy stop-and-go driving. On some models, the electric motor may even be able to “go it alone” at low speeds and light loads. When slowing down, the system recaptures energy, through what’s called regenerative braking. Hybrids generally also turn the gasoline engine off during periods of idling and restart it automatically, as needed, when accelerating.
Hybrid of a different color
The Hybrid option available now in GM’s full-size pickups is a little different. Actually, the system, which GM has wisely been terming a “mild” hybrid system, doesn’t boast hybridized propulsion at all. The electric system doesn’t help the gas engine in acceleration, either. So why is it called a hybrid? Well, the much-stronger-than-usual electrical system handles the load of the accessories, allowing the engine to be safely turned off at stoplights, to save gas, and restarted quickly when they turn green. The model it’s offered on still has the same 295-hp, 5.3-liter V-8, same four-speed automatic, and very similar performance.
The key component of this system is a starter/generator unit that’s mounted between the engine and transmission. The starter/generator is permanently engaged and moves with the engine crankshaft. For the generator function, the system’s rotor is attached directly to the engine crankshaft. When coasting or decelerating, the system goes into generation mode and charges the battery pack. If slowing to a stop, the engine will turn off completely at 13 mph or less, depending on the conditions, and the upgraded electrical system will take over vehicle functions. Simply lift off the brake and — presto — the starter/generator system quickly starts the engine, you apply the gas pedal, and off you go with normal V-8 gusto.
This more powerful 42-volt electrical system uses three large “deep cycle” lead-acid batteries stored together under the back seat. The battery pack is connected to the starter/generator unit, and it also provides power for the steering and braking systems.
The overall feel of the system going to work and the engine turning off while the vehicle is still moving is quite disconcerting at first. When decelerating to a stoplight with your foot on the brake, the engine stops and revs go to zero by the time you pass the 10-mph mark, such that the last portion of the stop happens in a sort of eerie silence. Once you come to a stop, you become aware that the only sound is a faint but steady buzzing — sounding kind of like an old AM radio or a power-company substation — that seems to be coming from just behind the dash. Releasing your foot from the dash causes a sudden start of the engine but no serious surge forward.
Conventional pickups use engine-vacuum power brakes and hydraulic power steering driven by an engine accessory drive belt, but since the Hybrid’s engine is programmed to cut out when approaching a stop, the power pack provides the assistance instead to keep it safe and help improve gas mileage. The power steering is an electro-hydraulic system, a unique design for the trucks that uses electrical power to build hydraulic pressure in the system. The assist system for the brakes is similar, with a pedal position sensor and an 1800-psi pressure valve to maintain peak pressure.
On the road, the power steering feels no less effective — and no more out of touch with the road — than the standard power steering system in GM’s full-size trucks. There’s a dead zone at center, and there’s no real feedback (our 4WD model had the recirculating-ball setup, likely less direct than the rack-and-pinion in the 2WD), and the ratio requires lots of elbow room, but all this can be expected on a full-size pickup. I was pleasantly surprised, however, with the feel of the electrohydraulic brakes. Pedal feel was nice and firm, and they seemed to stop the vehicle more intuitively than the standard power-brake system on the trucks, which can seem a little overboosted at times.
In almost all other respects, driving the Hybrid version of the Silverado is much like driving any ordinary full-size pickup. The ride is quiet and well isolated but a little bouncy; the seats are soft and wide and seemed very comfy for short trips.
Parking can be a bit harried, as there’s almost no creep function in either Drive or Reverse. Generally you have to tap the gas first to get it to creep forward, but the gas pedal is very touchy and a very light touch causes the truck to leap forward. Recalibration of the throttle to a more linear response would have helped here. The only other drivability quirk we noticed was a slight surging feeling while trying to maintain a steady 25-30 mph on congested city streets — probably as the regenerative braking cycled on and off.
The target buyer here is obviously quite different than those who look at the Prius, or even the Honda Accord Hybrid or the Lexus RX400h. This is a different, simpler, type of system, more likely to appeal to green-thumb contractors than frugal commuters or those who want to make a statement. Aside from the huge “hybrid” badges on the dash and tailgate, the Hybrid model looks just like the standard Silverado or Sierra, To cater to truck buyers, and take advantage of the electrical system’s generating capabilities, the Hybrid includes a powerful accessory power module that provides AC plugs and can operate “on site” as a reliable AC generator, cycling the gas engine on as needed.
When equipped with the Hybrid option, the Silverado 4WD model, as we tested, carries EPA ratings of 17 city, 19 highway. But in an initial 150 miles of combined driving — mostly urban and suburban stop and go, but gentle driving — we barely saw a measly 13 mpg altogether, and in a short, mostly level steady-driving highway stint, we saw about 17 mpg indicated on the trip computer. We suspect that, at least in the type of driving we did, the Hybrid saw about the same mpg as its standard-engine 5300 V-8 counterpart. Weather was mild in the week that we had the Hybrid, and the climate control was completely turned off for much of that time. Part of this big discrepancy is likely because the EPA city test is conducted with the engine fully warmed up. Our urban mileage consisted of several short 10- to 15-mile trips, and the engine wouldn’t shut itself off at idle until we’d driven for nearly ten minutes.
The Hybrid isn’t any less capable, though. Towing capacity can be up to 7800 pounds, and payload can be up to 1583 lb, and the Hybrid should be able to go anywhere dusty and out of the way you would take a normal Silverado.
Keeping up with the batteries
Maintenance is probably a concern for buyers of a vehicle that has some sophisticated new componentry, but we were assured the Hybrids don’t require any added standard maintenance versus the regular models. After many years the owner may need to change the coolant for the power inverter, and the batteries have a four-year lifecycle, but that’s about it. The batteries need to be disconnected — with an onboard switch — if the vehicle isn’t going to be driven for a month or more.
The package is available now on a limited basis, and it
isn’t at all available in the pickup-happy
There are many ways you can do better
fuel-economy-wise with a smaller pickup — like the base Ford Ranger, Toyota
Tacoma, Nissan Frontier, or Chevy
For forward-thinking companies that are going to buy a full-size truck either way, might be able to benefit from hybrid-vehicle tax incentives (although federal credits don’t apply here), and could save a little bit on their gas bills, then the Silverado Hybrid makes sense. And if GM can get these systems on most of their full-size trucks in the near future, that little gain in fuel economy could make a big difference.
2005 Chevrolet Silverado
Base price: $36,860
Engine: 5.3-liter V-8, 295 hp/335 lb-ft
Drivetrain: Four-speed automatic; four-wheel drive with active transfer case
Length x width x height: 227.7 x 78.5 x 73.9 in
Wheelbase: 143.5 in
Curb weight: 5008 lb
Fuel economy (EPA city/hwy): 17/19 mpg
Safety equipment: Anti-lock four-wheel disc brakes
Major standard equipment: Dual zone climate control; power windows, locks, and mirrors; leather seating; steering wheel controls; rear defogger; tilt steering; cruise control; keyless entry; AM/FM/CD sound system
Warranty: Three years/36,000 miles