Jentgen said that most retooling for the new models has been accomplished already; what remains will be finished over holiday break this month.
In a press conference in Pontiac, Mich., Thursday, GM North America President Mark Reuss sounded optimistic about the prospects for both trucks. Besides the improvements he described, he said that strength in the agriculture and energy businesses, plus continuing recovery in construction, are improving demand for pickups.
The timing of the makeovers is apt: GM's current models are looking dated and sales are slowing.
“The only way our timing could be better is if we could actually sell them today,” Reuss said.
The new Silverado and Sierra are a little sleeker than the current models.
Ruess said the 2014 models were designed to be more differentiated than every before. That's inevitably a challenge, given that both trucks are built on the same chassis, with the same engine choices and same three configurations: regular cab, extended cab (a smaller back seat and smaller rear doors) and crew cab (a full-size back seat and full-size rear doors). The most obvious differences are in the front end and grill of the models.
The Sierra's grill appears to jut out more than the Silverado's. The Silverado has two large-lens headlights on each side of the grill, compared with a single such headlight on each side of the Sierra grill.
Gas mileage and prices were not announced Thursday.
Ruess said that Sierras would have more upscale accessories and features as standard equipment, although they would be available as options on Silverados.
“From hood to hitch, these are the most refined pickups ever,” Reuss said.
Jeff Luke, GM's executive chief engineer for full-size and midsize pickups, described the technical changes in the vehicles during the press conference.
The biggest changes come with a new three-engine lineup for the pickups: a 4.3-liter V-6, a 5.3-liter V-8 and a 6.2-liter V-8. Luke said that these will incorporate several features to improve their efficiency; the most dramatic is “cylinder deactivation.” When these pickups are not heavily taxed – for example, cruising at moderate speed on level ground – they can operate on only four cylinders instead of all six or eight.
General Motors tried a similar feature – running certain large engines on variable numbers of cylinders – 30 years ago, but those engines developed bad reputations for mechanical trouble. In the last decade, GM, Honda, Chrysler and Mercedes-Benz have offered these variable-displacement engines with much better results.
The new trucks will offer new safety features, too, Luke said, including a forward-collision alert and a lane-departure warning.
Among other changes for trucks for 2014:
*A longer bed – 6 feet, 6 inches long – is available on crew-cab trucks in addition to the standard bed that is 5 feet, 8 inches long.
*The trucks are more aerodynamic. Luke said their coefficient of drag – a measurement of how much wind resistance they create – is 5 percent lower than the models they replace.
*Neither Sierra nor Silverado offer a manual transmission this year, according to specifications provided by GM. Both models use a six-speed automatic transmission.
*Rear doors on crew cabs are larger. Rear doors on extended cabs are hinged at the front. Both changes are designed to make it easer to get in and out of the rear seats in the trucks.
*Four-wheel disc brakes are now standard.