First Drive: 2009 GMC Sierra Hybrid and Chevy Silverado Hybrid TrucksI had a chance to spend a little time in GM's 2009 hybrid pickup trucks, the Chevy Silverado hybrid and the GMC Sierra hybrid. I hadn't driven GM's Yukon or Escalade hybrids (they're built with the same two-mode hybrid system) so I wasn't sure what to expect power-wise when I climbed behind the wheel of the new trucks. In three words, I was impressed.
Quick Look at GM's Hybrid SystemThe 6L trucks can run on four types of power:
- electric power
- V4 gas power
- V8 gas power
- a combination of electric and gas power
When a truck is in motion, a computer determines which of the four modes is best for the current conditions, making changes to optimize power and economy. After our road tests, a couple of the other drivers mention being annoyed by the movement that occurs when the system changes from electric to gas power. I have to disagree, and thought the operation was seamless, with no jerking motions between modes.
Power vs. Economy The hybrid system always attempts to balance power requirements with economy. For instance, if you're cruising along in V4 at a steady 60 mph, and you come to a slight grade, the truck's electric motor kicks in to increase power. You can expect the system to tap-in to the more gas-hungry V-8 any time power is needed -- when passing, traveling up steeper hills or pulling a load.
Monitor Your Driving in Real Time A gauge on the dash helps you see how your driving habits affect the truck's operation -- keep the gauge's needle within the green zone and you know that you're at the best efficiency for the situation you're in. Quick take-offs and hard acceleration put you out of the zone, a sign that you're wasting fuel. The gauge can be a good fuel-saving device if you pay attention to how your actions affect the truck's power needs, and then break those gas guzzling habits.
Variable Automatic TransmissionSilverado and Sierra hybrid trucks are equipped with a constantly variable transmission (GM calls it electrically variable), meaning there are no specific gear ratios. A computer senses the driving conditions and adjusts the transmission to the best ratio -- eliminating the typical jerking motion you feel when a transmission shifts up and down trying to find the right gear.
The transmission does have a manual mode (tap up/tap down control) that comes in handy if you need to downshift for any reason -- say to travel down steep grades or to control the truck's speed in slippery conditions. When manual mode is engaged, the computer allows you to shift between four predetermined gear ratios that are similar to those found in a conventional automatic.
I was fortunate to have Mark Cieslak, Vehicle Chief Engineer, in the passenger seat during my hybrid truck road tests. He said they had originally incorporated a tow mode into the transmission, but eliminated it after road tests indicated it wasn't needed.
The combination of engine, electric motor and transmission operation make the trucks feel and sound "different," not bad -- just different. It's a variation I think most drivers will quickly become accustomed to.
Regenerative Brake SystemGM's hybrid trucks have a regenerative brake system -- every time you apply the brakes it helps charge the hybrid battery.
I talked to Mark about the new brake system, asking how it had impacted brake pad life and the truck's stopping abilities. He said the hybrids' brakes perform better overall than conventional brakes, with a shorter stopping distance and longer pad wear.
Hybrid Truck Towing AbilitiesWe parked the Silverado and switched to a Sierra hybrid with a 6,000 pound boat and trailer on the back. Could I tell a difference in the truck's power when it was pulling a heavy load? Sure, but the difference was what I'd expect from any half-ton pickup truck under the same conditions. And as you'd expect, pulling a trailer required more use of the truck's V-8 mode.
- Towing Specs:
- 2WD Crew Cab: 6,100 pounds
- 4WD Crew Cab: 5,900 pounds
GM Hybrid Fuel Economy
- 2WD Crew Cab: 21 city / 22 highway
- 4WD Crew Cab: 20 city / 20 highway
Hybrid Truck Wrap UpMark mentioned to me that GM had performed extensive driving tests under all sorts of conditions, from the high mountains to the desert, just to make sure the trucks were durable and reliable. I'm anxious to spend more time in both trucks, but my first impression tells me that designers did their jobs.
Overall, the Sierra and Silverado hybrids don't sacrifice any of the things you'd find in the 1500 version of either truck.