General Motors Refreshes Its Top-Selling Trucks

PONTIAC, Mich. — General Motors introduced on Thursday revised 2014 versions of its bread-and-butter half-ton pickup trucks, the Chevrolet Silverado 1500 and GMC Sierra 1500.

At a glance, the trucks closely resemble the vehicles they are replacing. But both front and rear wheel well arches are more defined than those of the older models, subtly suggesting classic stepside pickup styling. Other visual changes include full bumpers, hood sculpturing, restyled headlights and relocated body side trim.

The big changes are under the hood, where three significantly revised EcoTec3 engines – a 4.3-liter V-6, a 5.3-liter V-8 and a 6.2-liter V-8 – are offered. The V-6 is a clone of the V-8s, with two fewer cylinders. All are built with aluminum blocks and cylinder heads and are light and compact for engines of their size.

While the displacement numbers are the same as last year’s offerings, the engines have been re-engineered with direct fuel injection, continuously variable valve timing and cylinder deactivation. Direct injection provides a measure of cylinder cooling, enabling a high compression ratio of 11:1. To accommodate the direct injection, the exhaust and intake passageways have been reconfigured and the spark plugs have been relocated, while the combustion chambers and piston tops have been shaped to better manage the spread of the ignition flame. A cylinder deactivation system helps trim fuel consumption.

The changes breathe new life into the family of G.M.’s venerable pushrod engines introduced in 1955 but revised many times since. While final fuel economy and horsepower numbers are not yet available, the automaker says the new power plants will provide more horsepower, more torque and better fuel economy than its current engines.

A 6-speed automatic is the only transmission offering. It is fitted with a system that downshifts to a lower gear when going downhill, using engine compression to reduce brake wear.

The suspensions are largely carry-overs, with independent dual control-arm systems in the front and a leaf-spring-mounted solid axle in the rear. Electric power steering replaces the hydraulic systems of the previous models.

While the truck cabs may look like those they replace, the structures are new and incorporate more high strength steel. Aluminum hoods help offset the weight of wider wheels, a larger battery and more substantial rear axles in V-8 models.

Both GMC and Chevrolet versions have been fitted with substantially revised interiors. Though similar, the GMC version has a more luxurious look, achieved in part with faux wood trim and visible stitching. A row of analog gauges now tops the speedometer and tachometer, and the climate control and infotainment systems have been given their own pod in the center of the dash.

G.M. introduced the two new vehicles to the press at the Michigan Motion Picture Studios in Pontiac. The studios were built as part of an effort to attract film business to Michigan in hopes of replacing auto industry jobs  thought by some to have been lost for good when G.M. and Chrysler went through bankruptcy. Now the auto industry has rebounded, while efforts to establish a film industry have floundered, so it’s not surprising that the vast studio was available for a winter vehicle introduction.

While sales of G.M. pickups are only a bit more than half of what they were during the automaker’s best years, the 2011 figures were over 30 percent better than those of 2009. Ford’s F-Series trucks continue to be America’s best-selling vehicle line, but the nearly identical Sierra and Silverado are a close second with combined sales of 564,300 in 2011. Ford F-Series sales totaled 584,917 for the same year.