Mr. Truck 9-28-09 | TheFencePost.com
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Mr. Truck 9-28-09

Kent SundlingGMC Sierra Hybrid

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I first drove the new GMT900 platform Tahoe SUV hybrid in 2007. Now GM adds to the list, I towed trailers with the GMC Sierra Hybrid and the Cadillac Escalade Hybrid comparing to a Yukon non hybrid. The 40 percent fuel economy improvement in city miles-per-gallon gets your attention. The nice warranty, 100k and eight-year warranty for the hybrid, five-year power train takes the risk out. Both hybrids and the Yukon towed the Cimarron 2H trailer well.

The full size GMC half-ton is EPA rated 20 city/20 highway … yes 20 in the city. That’s the story of hybrids, incredible mileage tooling around town. Part of that is contributed to regenerative braking, which charges the batteries when you brake. With Active Fuel Management, the truck can run on half of it’s cylinders so you can go nearly 500 miles one tank. All amazing stuff when you look at it all together. Just write that check for $42,790. The majority of the extra cost of the hybrid can be covered by a federal and state tax incentives.

Locking 3.08 rear axle with an Eaton locker and trailering package is standard equipment. Only available as crew cabs, which is the most popular cab configuration anyway. Today’s hybrid half-tons are limited in towing capacity by two factors: cooling requirements for the trucks’ electronic systems, and torque limitations in some of the transmission’s gear-set changes.

The two-mode hybrid powertrain uses an electrically variable transmission that houses two 60kW electric motors, two mode continuous electric ratio hybrid, four fixed gears and in between, has infinite gear options like a hydrostatic in a combine or hay swather.

At low speeds (Mode 1), the first electric motor, replacing the torque converter, drives the truck off the batteries up to 32-mph, and as far as one to two-miles, depending on charge levels.

At high speeds (Mode 2), the second electric motor, at the back of the transmission, works with the fixed gears to create an electronically variable transmission (EVT). The Active Fuel Management (i.e. cylinder shutoff) V8 also uses this electric boost to spend more time running in V4 mode to optimize fuel economy. The large 6.0L gas engine helps keep the truck in V4 mode longer while providing a steadier torque curve across RPMs for the transmission to manage. When I tow, I like having a larger engine. The 6.0L has torque is the right choice for power in a hybrid.

Future GM Hybrids are reported to double towing capacity and make a hybrid truck an option for most trailers. Commercial class 6 trucks are taking advantage of hybrids’ in city delivery trucks successfully, it’s become a tested technology.

Several auto makers are working on the same hybrid platform with their own unique application. The hybrid pickups have a few unique exterior features to set them apart from standard pickups. Most noticeable are the polished 18-inch wheels, which save weight, and the standard tonneau cover for better aerodynamics – cloth on regular models, a three-piece hard shell if you get luxury trim. The front air dam extends 11 mm further toward to the road. And GM’s characteristic chrome hybrid logo green-leaf is mounted on each front fender and the tailgate.

These trucks fit a 1.8-kilowatt-hour battery pack beneath the rear seat, and the two-mode hybrid transmission replaces the standard truck automatic. To offset the added weight, the front lower control arms and differential shaft are made of aluminum. And GM engineered a special hydraulic bushing to attach the cab to the frame, damping new vibrations created by adding the 300-pound battery pack.

They were really quiet, like a golf car, because these hybrids can run on their electric motors at speeds of up to 30 mph. These hybrids use regenerative braking to capture energy from braking and coasting and store it in the battery for future use.

An efficiency meter in the dash will tell you how well your are driving for the best economy. The dash readouts tell you when you are running on four cylinders or eight with active fuel management. It’s weird to look at the gauges when in mode one – no engine so no oil pressure or RPM’s on the tach. It’s odd looking at the front of the engine with no fan, no power steering pump or belts.

Cadillac Escape Hybrid

As big as it gets in a hybrid SUV with magnetic ride control, automatic rear and leveling control. It’s the fastest auto air suspension I’ve tested. Heated and cooled seats work for me. In the NAV system you can see where the power is coming from on the hybrid. Automatic windshield wipers and auto dim for the lights. I followed a truck that had dim tail lights and my lights didn’t auto dim. It does have 115-volt outlet which I missed on the Sierra hybrid. No spare, just a sealant kit with air. This Hybrid gets 20 city and 21 highway mpg all for $72,865.

Coil spring rear suspension is not my favorite for towing but the rear air leveling stays put on this Caddy. I like power tools like laptop, battery charger, air compressor so I really like the 110 volt outlet. Disappointed that the GMC Sierra didn’t have an outlet.

GMC Yukon with Flex-Fuel

GMC Yukon with 6-speed auto is a big improvement with the 5.3L gas engine. Plenty of room, optional integrated trailer brake controller, a good SUV for towing 8,400 pounds in a 4-by-2. GM jumped in with both feet on the ethanol bandwagon with the most flex-fuel models. It looks good when E-85 is a dollar cheaper than gas. At least GM is trying with hybrids, active fuel management (eight to four cylinders), flex-fuel, the Yukon with 5.3L and six-speed auto with double overdrives is EPA rated 14 mpg city, 20 mpg highway.

Both hybrids and the Yukon towed the Cimarron 2H trailer well. Cimarron has one of the easiest towing bumper trailers – I think it has to do with the shape of the V-nose from tongue to the outside wall. Being aluminum I’m sure helps.

Thanks to Transwest Truck Trailer RV for the Cimarron trailer, and for more information please visit http://trailerwest.com.

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Kent Sundling (alias “Mr. Truck”) spent 20 years wearing out pickup trucks as only a farmer could. With over 1 million miles pulling trailers, Mr. Truck has a unique collection of truck and farm stories that will educate and entertain. Mr.Truck gave up his bib overalls and John Deeres in his quest to save the farm and moved to the big city to sell trucks. After selling trucks for 10 years, this farmer now writes for eight magazines and owns over two dozen Web sites, helping folks find the “Right Truck.” If you have a question for Mr. Truck, you may contact him at his Web site, http://www.mrtruck.net.


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