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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:    

This 450-hp electric Lotus Evora is powered by Tesla and Chevrolet

When someone mentions an electric Lotus, the first thing that comes to mind is the Tesla Roadster, the California-based automaker's first vehicle. That car started life as an Elise before being heavily massaged and adapted by Tesla's engineers. In a similar spirit, the people at Onpoint Dyno are close to finishing Blue Lightning, a track-ready all-electric Lotus Evora. Blue Lightning uses a Tesla drive unit and a Chevrolet Volt battery pack, both mounted in the middle in place of the Evora's 3.5-liter Toyota V6. It's putting down about 450 horsepower at the wheels. The car was built for time attack sessions, so power is fed through custom forged wheels and super sticky Pirelli PZero Trofeo R tires, the same ones found on the last Chevrolet Camaro Z/28. There is a custom digital instrument cluster in place of the Lotus gauges. There's also a regen paddle on the left side of the steering wheel. With a full charge, Blue Lighting should go about 120 miles. While the car runs under its own power, it's only about 90 percent complete. It has no power steering, no firewall in between the seats and the motor and battery pack, no A/C, and a large hole where the shift lever used to be. Other final touches include fine-tuning the brakes and suspension. There is also a custom rear bumper coming that should make it look more like the new Lotus Evora 400. Onpoint Dyno expects the car to hit the track in the next month or so. Related Video:

Chevy Volt 'acceptable,' Nissan Leaf 'poor' in new IIHS safety tests

Ford C-Max Hybrid also scored "acceptable" rating. With US Nissan Leaf sales up almost 30 percent during the first half of the year, the only thing that might be able to stop the battery-electric vehicle is a good, stiff barrier. Unfortunately, thing's aren't always pretty when that happens in the real world, according to new tests from the Insurance Institute for Highway Safety (IIHS). Things with the Chevrolet Volt extended-range plug-in are a little bit rosier, though. The two plug-in vehicles were part of a batch of a dozen vehicles that just went through the IIHS's "small overlap" test, in which the driver's side front corner of the vehicle is crashed into a rigid barrier at 40 miles per hour. Out of the dozen, only the Mini Cooper Countryman was given a "good" rating. Five vehicles, including the Volt and the Ford C-Max Hybrid, were rated "acceptable," two were "marginal" and two, including the Leaf, were "poor." Plug-in vehicles are unique in the crash-test context because of their relatively large battery sizes. In the Volt's case, the driver had a "low risk" of injury, said the IIHS. But the Leaf's crash substantially pushed back the instrument panel and steering column, creating a scenario where the driver was "likely" to sustain leg injuries. The batteries in both the Leaf and the Volt passed safety tests specifically targeted at things like thermo and electrical properties and overall integrity. "Nissan is proud of the Leaf's 'Good' rating in all other IIHS tests, a 4-star NCAP rating from NHTSA and its IIHS Top Safety Pick rating in all previous years since the car's release," the company said in an e-mail sent to AutoblogGreen. "As for the performance of the 2014 Leaf in the 'small overlap frontal test,' Nissan will continue to review these and other results from the IIHS 'small overlap frontal test' as we seek opportunities for improvement." Check out the IIHS's press release and small car crash-test video footage below. Range of ratings: Small car ratings run the gamut in challenging small overlap front test The Mini Cooper Countryman is the only small car to earn a good rating among the latest group of 12 cars subjected to the Institute's small overlap front crash test. Two electric models and a hybrid also are in the mix, with varied results. The electric-powered Chevrolet Volt (with a gasoline engine "range extender") earns an acceptable rating, while its battery-electric rival, the Nissan Leaf, earns a poor rating.