The Coming Pickup Truck Powertrain Dilemma: Choosing The Right Engine For Your Truck
By: Mike Levine Posted: 05-12-08 10:29 PT
© 2008 PickupTrucks.com

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As if choosing the right truck wasn't difficult enough, thanks to the dizzying array of wheelbases, cab configurations and classes on the market, spiking fuel prices and all-new powertrain options are poised to make the dilemma even tougher in the near future.

Say you're buying a full size truck today and need to select an engine. If you're looking for a GM pickup, powertrain choices are limited to a relatively simple set of six or eight cylinder gasoline engines or a diesel V8.

Choosing the right motor to fit your needs boils down to a few simple questions: How far are you going to drive annually? Are you going to tow? If yes, is what you're towing light or heavy? Do you want the lower upfront cost of a gas engine or the superior pulling power and towing fuel economy of a diesel?

Generally speaking, the 4.3-liter V6 and 5.3-L gas V8 are best for light towing (up to 8,900-lbs) or for drivers who won't be towing at all, while the 6.0-L gas V8 is the best option for moderate to heavy towing (up to 10,500-lbs). The 6.6-L diesel V8 is best for the biggest pulling needs (up to 16,700-lbs w/5th wheel hitch).

In the next two years, though, GM's engine choices will become far more complex. In addition to knowing how they intend to use their new truck, buyers will also have to anticipate the kinds of conditions in which they'll drive in order to figure out which is the best engine to put under the truck's hood.

This fall GM will offer a gasoline hybrid engine option for its 2009 model year light duty pickups. The new 6.0-L V8 'two-mode' hybrid promises 40% better fuel economy in city driving and 25% better mileage overall compared to a comparable V8. GM also promises it will tow up to 6,100-lbs - though you'll lose nearly all the fuel economy benefits.

The big mileage gain will cost a lot, though. Prices haven't been announced for the pickups but the two-mode setup is already available for GM's full size SUVs, where it carries an almost $5,000 premium (after $2,200 federal tax credit) over a conventional V8 SUV.

Another component being added to the mix is a six-speed transmission for the light-duty Chevrolet Silverado and GMC Sierra pickups, which GM will begin delivering before the end of 2008. The transmission will be paired with a new 6.2-L V8 gas engine.

Gary White, GM's vehicle line executive for full size trucks, said he expects the six-speed gearboxes will add up to 5-percent better fuel economy over the current four-speed transmissions. With larger displacement they'll also have more power. No word on cost.

For 2010, things will only get hairier, as a new 4.5-L V8 diesel engine will arrive for GM's half-ton trucks. It's expected to deliver more than 310-horsepower and 520 lb-ft of torque, along with 25-percent better mileage than comparable gasoline engines. Tow ratings for this setup haven't been announced yet, but they should be at least 10,000-lbs. It will likely cost $3,500 to $5,000 more than a comparable 6.2-L gas V8.

An enhanced 6.6-L diesel V8 for GM's heavy duty pickups will also debut in 2010 that will meet tough new emissions regulations going into effect the first of that year. Relative to current heavy-duty diesels, fuel economy in the new 6.6-L could take a step backward to meet stricter exhaust controls. The price premium on this diesel is expected to be about $6,000 to $7,500 over a gasonline version.

Once the new engines debut, buyers who want a conventional gas engine and tow light loads should probably stick with the 5.3-liter V8. For heavier loads and low annual driving mileage, though, the new 6.2-liter V8 will be best.

The two-mode gas hybrid pickups make the most sense for buyers in urban environments who face moderate stop-and-go traffic and have seldom or light towing needs.

Hybrid capabilities could improve over the long term if 'plug-in serial hybrid' powertrains, like the upcoming Chevrolet Volt will use, become a reality in pickups. A plug-in serial hybrid could potentially tow as much as a diesel heavy duty but with better fuel economy.

For buyers who use their trucks more heavily, especially when it comes to towing, a diesel truck will still be the best choice - assuming the current 18% premium that diesel fuel carries over regular gasoline doesn't grow another 8% to 10%, or more, over the next few years. The 4.5-liter diesel V8 that's coming in 2010 should work for all but the biggest towing needs, which is where the new 6.6-liter diesel V8 will come in. In addition to their increased capabilities, diesels still beat both hybrids and gasoline engines when it comes to operating efficiency across a wide range of heavy tasks.

GM isn't the only manufacturer whose engine lineup is getting more complex. Chrysler will soon offer a two-mode hybrid Ram 1500 pickup, as well as a Cummins V8 light-duty diesel engine. There are also rumors of a second light-duty diesel V6 coming to Dodge trucks in the near future, and Ford will bring a new 4.4-liter diesel V8 to market for the F-150 and Super Duty pickups, along with new twin-turbo direct-injection EcoBoost gasoline V6 and V8 engines.

For its part, GM has created a Propulsion Application Map (pictured above) to help buyers navigate these complex powertrain choices. Split into four sections along two axes, the map is intended to help buyers make an engine choice based on how and where they plan to drive.

The X-axis is devoted to driving conditions, with Stop & Go on one side, referring to city traffic, and Continuous on the other, meaning highway traffic. The Y-axis plots towing needs, from Consumer usage, meaning light loads like a family might use, to Commercial usage, which refers to heavy loads that a business or institution would need from their trucks.

Where a truck falls on the map depends on its powertrain, intended purpose and operating environment.

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