Re the new 2020 Silverado:
"Superficially, the choice comes down to horsepower or fuel economy. A 4x4 with the V8 gets 17 mpg combined, while the diesel gets 25 mpg combined. But the V8 makes 420 horsepower, to the diesel’s 277 horses. So the gas truck is quick and thirsty while the diesel is slower and thriftier, right? Yes, but that’s not all there is to it.
While the big V8 is unquestionably quicker when you’re going wide-open-throttle, the two engines don’t feel wildly different in normal driving. Both engines make plenty of torque—460 lb-ft of it—but the diesel delivers it by 1,500 rpm, while the gas engine needs to rev up to 4,100 rpm. As a result, the smaller six feels effortlessly powerful, while the 6.2-liter always seems to be working harder (because it is).
And this might confound your expectations, but the diesel is smoother than the gas engine. A straight six is inherently balanced, and the diesel’s advanced fuel injection system smothers all but a trace of compression-ignition clatter. The fuel injection system runs at 36,250 psi, with nine-hole injectors delivering fuel up to 10 times per combustion cycle.
With that kind of precision, you can fine-tune not only power output, but noise and refinement as well. The difference between the engines is most noticeable in part-throttle cruising on flat roads, where the diesel is near-silent but the V8 is cutting cylinders, which increases efficiency but results in noticeable changes in both the exhaust note and vibration making its way to the cabin.
Towing is one area where the V8 has a definite advantage, with the 6.2’s tow rating topping out at 13,400 pounds to the diesel’s 9,300 pounds. So if you’re towing the sort of boat or RV that’s in that grey area at the top of a 1500 truck’s tow rating, the 6.2 is the better bet. However, towing at altitude might send the advantage back toward the Duramax, since its turbocharger can compensate for altitude while a naturally aspirated engine will lose power the higher you climb."
Dang. Gotta go drive one of these I6 Duramaxes.