2003 Gmc Yukon Xl 1500 Slt Sport Utility 4-door 5.3l on 2040-cars

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GM trucks get hybrid versions, but you'll probably never see one

A few years ago, General Motors sold hybrid versions of its Chevy Silverado and GMC Sierra pickups. They weren't very good, using GM's old two-mode hybrid system that resulted in only negligible fuel economy gains. But GM's trying again, launching eAssist models of the 2016 Silverado and Sierra that are said to offer 2-mpg improvements in city, highway, and combined fuel economy ratings. Problem is, you probably won't be able to get one. Only 700 eAssist trucks will be made for the 2016 model year – 500 Silverados and 200 Sierras. When you consider that GM moved 824,683 examples of its light-duty pickups in 2015, this small run represents 0.08-percent of all Silverado/Sierra production, and GM says it "will monitor the market closely ... and adjust as appropriate moving forward." But that's not the only limitation. The eAssist trucks will only be sold through California dealers. For the Silverado, eAssist can only be optioned on the 1500 Crew Cab 1LT 2WD model, and for the Sierra, the fuel-saving technology is solely available on the 1500 SLT Crew Cab 2WD model with the SLT Premium Plus package. Granted, in terms of the Sierra, that means you get niceties like LED headlights and taillights, Apple CarPlay and Android Auto, Bose premium audio, heated seats and steering wheel, lane keep assist, and more. In the trucks, eAssist combines a small electric motor and 0.45-kWh battery pack with the pickups' 5.3-liter V8. GM estimates total output of 355 horsepower and 383 pound-feet of torque – no more horsepower than the non-eAssist trucks, but three more pound-feet of torque. GM says the eAssist trucks can tow up to 9,400 pounds, and the battery only adds 100 pounds to the trucks' weight. The electric motor provides 13 hp and 44 lb-ft of torque for a boost of acceleration off the line, or during passing. It also allows the engine to run in four-cylinder mode for longer periods of time. eAssist uses regenerative braking to help power onboard electrical systems, and adds start/stop to the powertrain. Finally, the so-equipped trucks have a six-percent improvement in aerodynamics, thanks to a soft tonneau cover and active grille shutters in the front fascia. Great news is, the eAssist option is relatively inexpensive, only costing $500. But good luck getting your hands on one.

Chevy's 6.6-liter Duramax is pretty much all new

To say there's a heated battle in heavy-duty pickups is an understatement, with Chevrolet, Ford, and Ram constantly trading blows of increased torque, horsepower, and towing capacity. The latest salvo is the revised, more powerful turbo diesel 6.6-liter Duramax V8 in the 2017 Chevy Silverado. It has 910 pound-feet of torque, an increase of 145, putting it nearly level with the Ford Super Duty. Here's a closer look at where those gains come from. How exactly did Chevrolet add all that torque plus 48 horsepower? The automaker essentially took a fine-tooth comb to the entire engine. Chevy says it changed 90 percent of the V8, and the cumulative effect of those small changes adds up to big increases. As you might guess, the turbocharger is updated. The larger unit features electric actuation of the variable nozzle turbine (VNT), and what Chevy calls a double axle cartridge mechanism that separates the VNT moving parts from the housing. That helps with heat performance as well, with a claim that the exhaust side of the turbo can run continuously up to 1,436 degrees Fahrenheit. Helping that cause are six exhaust gaskets made of Inconel - an nickel alloy that contains chromium and iron – and upgraded stainless steel for the exhaust manifold. Despite having the same cast iron cylinder block, albeit with some minor enhancements, the engine has new cylinder heads, pistons, piston pins, connecting rods, and crankshaft, which have all been upgraded to handle 20 percent higher cylinder pressures. Alongside the increase in pressure, Chevrolet also increased the cylinder head's structure with a honeycomb design. The pattern features high-strength aluminum with dual layer water jackets that not only improve strength, but also optimize water flow for better cooling. For 2017, the cylinder head also benefits from integrated plenum that aids the engine in getting more air under heavy loads. The cylinder head isn't the only component to get a minor update, as the pistons have a larger diameter pin for improved oil flow. The same detailed improvements has been bestowed to the humble connecting rods (second in our hearts only to the inanimate carbon rod). The new design has the bolts oriented roughly 45-degrees to the rod instead of parallel. The angle split design, as it's called allows for easier passage through the cylinder.

Weekly Recap: Auto execs face life in prison for recall delays under proposed legislation

The stiff punishments are part of broader transportation legislation, but clearly McCaskill has automakers in her sights.
Missouri Senator Claire McCaskill threw down the gauntlet this week, proposing a bill that could send auto executives to prison for life if they were found to have delayed a recall. She also wants to eliminate the limit for fines for auto safety violations, which are currently capped at $35 million.