Truck sales may have taken a beating over the past few years, but they're still among the top-selling vehicles in the U.S., so it's not surprising that automakers are continuing to invest heavily in offerings like the updated 2011 Chevrolet Silverado Heavy Duty, which is making its debut at the 2010 Chicago auto show.

Though it may look nearly identical to the existing Silverado HD, save for small refinements to the hood, grille and front bumper, don't let that fool you. The real story lies beneath, where Chevrolet has made big improvements to the structure and powertrain that the company promises will make this truck a segment-leader in towing and hauling, all the while burning cleaner and making more power.

Starting under the hood, Chevrolet is rolling out the latest version of the 6.6-liter Duramax turbodiesel V-8, which has been reworked internally to increase strength and improve efficiency. How much, Chevy won't say yet, but the company promises that the new mill will put out "significantly" more power than the current engine, which churns out 365 hp and 660 lb-ft of torque. If you don't need that much twist, there's always the 6.0L Vortec gasoline V-8 which is mostly unchanged save for a new camshaft that increases torque at low RPM.

If you want to sample Chevy's latest gizmos, though, you'll want to stick with the oil burner. Internally, the Duramax has seen its oiling system upgraded substantially and the engine can now be run on B20 biodiesel without any modification. Altogether, Chevy says the improvements are good for an 11% increase in highway fuel economy and a range of 680 miles thanks to a 36-gallon fuel tank.

Those aren't the only new tricks the Duramax has learned either. With a urea solution injected into the exhaust stream from a 5.3-gallon tank that will reportedly last 5,000 miles between fill-ups, Chevy says it has reduced NOX emissions by 63%. A new diesel particulate filter now lasts for 700 miles between regenerations, a full 300 miles longer than the outgoing truck.