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Towing 5,000 Pounds

We tried out the Silverado Hybrid with a 5,000-pound, 22-foot Sea Ray boat and double-axle trailer hanging off its back end. The first 30 seconds driving the Silverado were the most incredible of the hour we had it. We thought the truck might sense the boat's additional weight and start with the gas engine engaged to prevent damage to the hybrid powertrain, but it pulled away with only the golf-cart-like hum of its electric motors, then stayed in full electric mode until almost 15 mph! There was no strain as it did this, just plenty of torque and power. The performance was diesel-like. We barely felt the V-8 kick in as the tach jumped out of auto-stop mode and started registering the gas engine's RPMs.

What's amazing is to think how much fuel we saved just getting the combined 11,000-pound mass of the truck and trailer rolling from a dead stop. This is what makes the Silverado Hybrid such a fuel-efficient vehicle in city driving, loaded or not.

Entering the freeway was worry-free and fast – even with the truck's stout 3.08 rear axle. We had no issue merging with traffic, which was flowing by at 65 to 70 mph. Again, performance was on par with a diesel truck, not gasoline. Electric motor noise intruded into the cabin as we accelerated onto the highway, but it was audibly less intense than some turbos we’ve heard compressing air in heavy-duty oil burners. Unlike most diesel pickups, there was no turbo lag. Torque was immediately available.

"The [hybrid] system has the torque delivery of a diesel," said Mark Cieslak, GM's chief engineer for full-size hybrid trucks. "It's always there for you. That's how it feels. It pulls like a mule. The other part of it is you don't get the cadenced shifts like a diesel [when climbing hills]. It's glass-smooth. The transmission always finds the optimal ratio for you without hunting."

With extra aerodynamic drag from the boat, the 6.0-liter V-8 stayed in eight-cylinder mode at speeds above 60 mph. This leads us to believe that when GM's half-ton 4.5-liter V-8 diesels arrive next year, they'll probably prove to be more efficient for frequent medium- and long-distance towing applications than the Silverado Hybrid.

The biggest negative, compared to conventional diesel-powered and gas pickups, is the Silverado Hybrid's lowly 6,100-pound maximum tow rating. Heavy-duty pickups can tow two to three times that much, and the 6.0-liter V-8 Silverado half-ton with a six-speed automatic transmission can pull up to 10,700 pounds. Part of the limitation is due to the hybrid's tall 3.08 rear axle, but it's mostly thanks to cooling requirements for the truck's sophisticated electronics. The heavier the trailer, the greater the heat load.

We expect the Silverado Hybrid and future Silverado diesel half-ton to be similarly priced, so it will be critical to think about how and in what environment you’ll use the truck before purchasing either.

Unlike GM’s conventional diesel and gas pickups, the Silverado Hybrid doesn’t have explicit tow/haul mode gear-swapping logic to hold RPMs during acceleration or to help grade-brake during long mountain descents.

"With the electronically variable transmission, you have [the equivalent of] tow/haul mode," Cieslak said. "It gives you optimal gearing all the time. Grade-braking is the same deal. [The EVT] gives you the benefit of the [automatic] braking that you need. We cadence the hybrid transmission, so if you tap the brake it behaves just like tow/haul mode."

Reverse is also unconventional. The gas engine doesn't drive the truck backward, but its electric motors spin backward to move the truck in reverse.

The Silverado Hybrid has three brake systems that work together to slow the truck: standard four-wheel disc brakes, the electric motors in the transmission, and two-stage hydraulic regenerative brakes that use the electric motors to capture and store brake energy in the truck's batteries while reducing forward momentum. The calibration between the brake systems was perfect — incredibly smooth and imperceptible as they handed off speed-scrubbing responsibilities.

What We're Thinking

Within the Silverado Hybrid's operating range, GM has created what we think is the smoothest-operating, most-efficient half-ton pickup available today, though it will take a longer drive to see if its durability is up to its hype. We recently drove a two-mode Chevrolet Tahoe Hybrid that suffered a software glitch that took the braking and stability control systems offline and forced us to swap out for another vehicle. Not good, but from what we understand, GM found and fixed that unique condition.

Assuming the Silverado Hybrid launch happens without further delay or glitches — and the price is right — hard-working owners are certain to be pleased with the truck they've bought. They can also grin as they pass LS 600h drivers, knowing their two-mode "Cowboy Cadillac" is more efficient than the higher-profile Lexus hybrid.

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