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Why an independent rear suspension for GM's new, full-sized SUVs wasn't easy

A Motor Trend report last month laid out how Cadillac's 4.2-lier twin-turbo Blackwing V8 could be an orphan due to cost concerns in the GM empire. Last-minute chassis changes to Cadillac's new sedans and XT6 crossover led to engine bays that couldn't fit the Blackwing. On the SUV side, according to the report, the new independent rear suspension for big people haulers cost so much to implement that GM ruled out reworking the Escalade to accept the Blackwing. At least one commenter rightly asked how could a suspension swallow that much money. A new piece in Motor Trend has the answer. The excellent Alissa Priddle spoke to Tim Herrick, GM's executive chief engineer for full-size trucks, about why the clean-sheet IRS cost "multimillions of dollars."  First, GM would need to build a new body shop at the Arlington, Texas plant that assembles the automaker's big SUVs to stamp the numerous wholly new parts and panels accommodating an IRS. Then GM would need to design and pay for a new assembly process. On top of those up-front costs, there was the incremental cost of the four-link IRS components being more expensive than those in the trucks' former leaf-sprung solid axles. Herrick endured so many rejections for so long that he remembers the date and time when he got approval for the new unit. He said it came down to a meeting where he told a higher-up, "I'll make you a deal: If we get to the reveal, or if we launch this and you think this was a dumb idea, I'll hand you my badge and let you walk me out." Head to Motor Trend to read the full story. Based on Herrick being on stage to help present the new SUVs to the press, and on our First Ride in the new Chevrolet Tahoe and Suburban at GM's Milford Proving Grounds, it appears this will have a happy ending for all involved. Furthermore, since Herrick worked on the T1 platform that supports the big SUVs as well as the light- and heavy-duty pickups, he understood the demands on the commercial side, too. That could be why when Roadshow asked Tim Asoklis, chief engineer of the Tahoe and Suburban, if the new IRS could endure life in the Chevrolet Silverado and GMC Sierra, Asoklis answered, "Oh, absolutely." Related Video:    

Should heavy-duty pickup trucks have window stickers with fuel mileage estimates?

If you were to stroll into your nearest Chevrolet, Ford, GMC, Nissan, or Ram dealership, you'd find a bunch of pickup trucks. Most of those would have proper window stickers labeled with things like base prices, options prices, location of manufacture, and, crucially, fuel economy estimates. But you'd also run across a number of heavy-duty trucks with no such fuel mileage data from the Environmental Protection Agency. The EPA doesn't require automakers to publish the valuable miles-per-gallon measurement for vehicles with gross weight ratings that exceed 8,500 pounds. That makes it difficult for consumers to compare behemoths powered by turbocharged diesel engines – between one another, and between smaller, gasoline-fueled trucks. Consumer Reports doesn't think it should be this way, and it's spearheading an effort (PDF link) to get the government to require manufacturers to publish fuel economy estimates. In its own testing, CR found that heavy-duty pickups powered by Ford's Power Stroke, GM's Duramax, and FCA's Cummins diesel engines (which doesn't include the Ram's EcoDiesel) get worse fuel mileage than their lighter-duty gas-powered siblings. We're not so sure HD-truck buyers are unaware of this fact – big diesels don't really come into their own until big loads are placed in their beds or attached to their trailer hitches. Under heavy workloads, the diesel trucks will almost certainly return greater efficiency than a similar gas-powered truck. What's more, HD trucks with lumbering diesels in general make the driver feel more confident while towing due to greater torque at low engine RPM than gas trucks. They also offer greater max-weight limits. Still, we agree EPA fuel mileage estimates should be offered for heavy-duty pickups. And we think the comparisons provided by Consumer Reports might be interesting to potential buyers. Click here to see the results of CR's tests, and let us know what you think using the poll below. Related Video: Featured Gallery 2017 Ford F-Series Super Duty: First Drive View 22 Photos News Source: Consumer Reports Government/Legal Green Read This Chevrolet Ford GMC Nissan RAM Fuel Efficiency Truck Commercial Vehicles Diesel Vehicles poll gmc sierra hd chevy silverado hd

2014 Chevrolet Silverado and GMC Sierra debut all-new designs, three new engines

General Motors has finally dropped the curtain on the 2014 Chevrolet Silverado and 2014 GMC Sierra. Both trucks have undergone substantial revisions with updated versions of the company's 4.3-liter V6, 5.3-liter V8 and 6.2-liter V8 engines. In a shot across the bows of both Ford and Chrysler, GM says it won't use a V6 engine adapted from passenger car applications. Instead, it developed the 4.3-liter engine based on its proven truck-duty architecture.
All three mills will boast direct injection fuel systems as well as a new cylinder head design. Combined with a revised piston, the new engines feature a smaller combustion chamber with a compression ratio of 11:1 or higher depending on the application. Cylinder deactivation and continuously variable valve timing are all part of the recipe, and each engine is paired with a six-speed automatic transmission with auto grade breaking. So far, no fuel economy or horsepower figures have been released, though GM says the new engines will best their predecessors in both areas.
Outside, the trucks feature a number of enhancements to reduce drag and wind noise, and GM claims both the Silverado and Sierra will offer buyers some of the quietest cabins in the class. Extended cab models now feature front-hinged rear doors to allow easier access to the back passenger area, and Crew Cab buyers can now select between a five-foot, eight-inch bed or a six-foot, six-inch bed. Buyers with a mind toward going off road will also rejoice in the return of the Z71 package, complete with Rancho shocks, front tow hooks and additional under-body protection.