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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:    

Motor Trend wheels the 2015 Corvette Z06

The new Chevrolet Corvette Z06 is capable of some absolutely wild metrics. Want proof? Carlos Lago from Motor Trend is here to break it all down. 60 miles per hour? 3.2 seconds. 60 to 0? 91 feet. Lateral acceleration? A staggering 1.16g, a figure that is the highest MT has ever recorded for a vehicle that isn't a race car. It's an utterly astonishing piece of work, this Z06, and just when you think it can't possibly get any more impressive, Randy Pobst hustles an auto-equipped Z06 around Road Atlanta in just 1:30. Aside from the eight-speed auto, Pobst's Z06 had the most aggressive aerodynamic package, the so-called Stage III. Take a look at the 650-horsepower Z06 in Motor Trend's latest video.

Recharge Wrap-up: EV torque secrets, UC Davis maps future of biofuels

A UC Davis white paper maps out "Three Routes Forward for Biofuels," balancing investment risk with carbon benefits. The first option is "incremental," in which we tinker with the existing biofuel manufacturing infrastructure for small improvements over time. The "transitional" plan suggests integrating cellulosic production and other innovations with existing operations. The third route, called "leapfrogging," would mean building refineries based on new technology such as cellulosic and algae-based biofuels. The paper suggests ways the US could use these three routes together in different areas, and predicts the payoffs in terms of carbon emissions could be significant if the right people are willing to risk the capital. After all, financial advisers are always telling investors to diversify their portfolios to manage risk and rewards in the same way. Read more over at the UC Davis Institute of Transportation Studies. The Formula E Long Beach ePrix will offer free admission. The seventh round of the inaugural all-electric race season, which was moved from Los Angeles to the streets of Long Beach, will offer fans free grandstand and general admission. The race, which takes place on April 5, 2015, will use a 1.6-mile portion of IndyCar's Grand Prix of Long Beach. Read more at LA Times. Polaris is now offering its 2015 GEM electric vehicles, including the new street-legal eM1400 LSV. The passenger and utility vehicles come in two- to six-passenger configurations, many of which are street legal on roads with posted speed limits of up to 35 miles per hour. The eM1400 LSV utility vehicle seats two, offers 1,250 pounds of payload, 1,250 pounds of towing capacity, a top speed of 25 mph and a range of up to 45 miles. Its on-board charger plugs into any standard 110-volt outlet. Read more at Hybrid Cars and check out all the different configurations yourself at the Polaris website. In EVs, more torque does not always equal faster. Green Car Reports found this out when driving the Fiat 500e (with 147 pound-feet) against the similarly weighted Chevrolet Spark EV (with 400 pound-feet). The secret is, at least in part, in the gearing. The Fiat has a 9.6:1 reduction gear, making it quicker at lower speeds despite having far less available torque, while the Chevy uses a 3:1 ratio. The trade-off though, is in top speed. Furthermore, Chevy electronically limits the torque delivery at low speeds, as 400 pound-feet is a lot of launch for the little Spark EV to handle.