Silverado & Sierra Hybrid Trucks

• August
• 25

2:23 am Trucks

When the 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, I heard a couple of people say they felt the movement that occurred when the system changed from electric to gas power was annoying.

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 will kick in to increase power. Expect the system to tap-in to the more gas-hungry V8 when you need more power — when passing, traveling up steeper hills or pulling a load.

The transmission does have a manual mode (tap up/tap down control) that’s 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 pre-determined 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.

Silverado 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.

We parked the Silverado and got into 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.