The highest-volume vehicle GM sells in North America is a full-size pickup truck—one that likely also contributes outsize profits from each of its hundreds of thousands of units.

So the launch of the 2019 Chevrolet Silverado Saturday night before the Detroit auto show was a big deal for the company.

Like every other new vehicle produced for a new model year, big thirsty pickup trucks have to deliver higher fuel-efficiency ratings at the same time they add new features and boost their capabilities.

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The highest-efficiency version of this year's Silverado is rated at 20 mpg combined by the EPA, against 23 mpg combined for the Ram 1500 EcoDiesel (the highest-ranked 2017 pickup) and 22 mpg combined for the best 2018 Ford F-150.

We got only partial information on the 2019 Silverado line from Chevy last night; full details, ratings, and specifications won't start to arrive for three or four months.

But one spec we did get stood out: the 2019 Silverado is 450 pounds lighter than a comparably equipped 2018 model. That's huge.

2019 Chevrolet Silverado

2019 Chevrolet Silverado

The weight reduction, Chevrolet said, comes from extensive use of several grades of high-strength steel—they make up 80 percent of the truck's steel components—and GM's mixed-materials strategy.

While the competing Ford F-150 pickup has a fully aluminum body—including its cab and bed—on a steel frame, Chevy has mixed it up. All "swinging panels" (doors, hood, tailgate) are made of aluminum.

The frame, cab, and bed remain steel, with various individual structural pieces and running-gear components of other materials, including second-stage springs made of composite material—just as they are on the Corvette sports car.

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The bed of the pickup is the "working end" of the truck, like the head of a hammer, said GM product chief Mark Reuss, who added a sly dig at Ford: "You wouldn't want an aluminum hammer, would you?"

As always, ever more sophisticated computer modeling allows big car companies to simulate their designs before a single prototype is built.

That modeling shows how the design will perform in a crash, and calculates where the design engineers can remove ounces and pounds from the structure.

Chevy's weight reduction of 450 pounds is exactly twice the 225 pounds Fiat Chrysler said it had removed from its new Ram 1500 pickup, the third of the three high-volume domestic full-size pickups.

2019 Chevrolet Silverado 'aero curtain' in front fender

2019 Chevrolet Silverado 'aero curtain' in front fender

2019 Chevrolet Silverado

2019 Chevrolet Silverado

2019 Chevrolet Silverado cab-roof spoiler

2019 Chevrolet Silverado cab-roof spoiler

Along with lightweighting applied to every piece of its new pickup truck, GM has worked extensively on the aerodynamics of what is fundamentally a large, bluff, high-drag shape.

Rather than fit a full-size bed cover to reduce airflow turbulence inside a large open pickup bed, the Silverado's engineers spent thousands of hours on a very carefully crafted spoiler that sits at the back edge of the cab roof.

Its sole mission (beyond housing the high-mounted third brake light) is to lift the departing airflow over the open bed so lands at the back end, where another spoiler at the top of the tailgate smooths its path past the vehicle.

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The final version, according to Chevy, produced a 7-percent reduction in drag. That's a major improvement in a discipline where tenths of a percentage count.

So-called aero curtains at the leading edges of the front sides pull air inside the fender and direct it past the front wheels to reduce turbulence in the wheel well.

Then there are powertrains, only a few details of which Chevy revealed.

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

The 2019 Silverado will offer a newly developed Duramax 3.0-liter inline-6 turbodiesel, a layout chosen over the V-6 layout used by Ford and Ram so GM can get the catalytic converters as close as possible to the turbo's exhaust port.

The addition of a diesel engine brings GM's big pickups in line with those from Ram, which pioneered its 3.0-liter V-6 EcoDiesel in 1500-class trucks for the 2014 model year, and Ford, which added a 3.0-liter Power Stroke V-6 turbodiesel for 2018.

The truck will continue with updated versions of the current 5.3- and 6.2-liter V-8s, and the diesel and 6.2 will be paired with a 10-speed automatic transmission as well.

Both V-8s will include what GM calls Dynamic Fuel Management, a more sophisticated form of its previous cylinder-deactivation system. The new feature can shut off fuel for one to seven cylinders, on the fly, depending on engine load.

While the 2019 Silverado will offer six engines and transmissions, Chevy engineers refused to specify the transmission for the 5.3-liter V-8 or the other engines.

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

2019 Chevrolet Silverado, 2018 Detroit auto show

Chevrolet said nothing about either its eAssist mild-hybrid system or a more powerful 48-volt enhanced start-stop system, nor did the word "hybrid" occur at any point during the presentation—let alone "plug-in."

The full-size pickup revealed in the form of the 2019 Chevrolet Sierra lineup will also launch as a GMC Sierra later this year. Both trucks will go on sale sometime during the middle of 2018.

For all the latest about the (very few) green-car concepts and other updates at the North American International Auto Show, see our Detroit auto-show news page.

General Motors provided airfare, lodging, and snacks to enable Internet Brands Automotive to report on the 2018 Detroit auto show.

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