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GM's MPG overstatement could affect 2 million vehicles

Late last week, GM admitted that three of its large SUVs fuel economy window stickers did not match their actual efficiency ratings, and so the vehicles couldn't be sold. The stickers on the 2016 Chevy Traverse, GMC Acadia, and Buick Enclave said their ratings were one to two miles per gallon better than they should have been. Officially, the number of affected vehicles sits at about 60,000. But Consumer Reports makes a good point: what's up with all of the previous model year SUVs that are basically the same vehicle? To wit: the 2016 model year vehicles are not substantially different than the 2015 or the 2014, or even going all the way back to 2007. On the EPA's fuel economy website, all of these older models will "have better stated fuel economy numbers than the new vehicles in GM's dealerships," Consumer Reports noted. CR's best point, and the one that makes the 60,000 number potentially grow to 2 million if all of the vehicles built on this platform are affected, is that "[i]t seems unlikely that the company would change the powertrain on these carryover models so late in their model cycles in a way that would cause a dramatic, negative impact on fuel economy." GM says that earlier model year SUVs are not affected and the EPA did not respond to CR's question about the potential for more discrepancies. We've seen automakers reverse course before, so if GM has to come out with a mea culpa soon, don't be surprised. GM is rushing corrected stickers to dealers so that the SUVs can be sold again, but a fix for the already-sold vehicles could be trickier to solve. Related Video: Related Gallery 2013 GMC Acadia View 16 Photos News Source: Consumer Reports Government/Legal Green Buick Chevrolet GMC Fuel Efficiency mpg gmc acadia chevy traverse

Weekly Recap: Revisting the BBC report that ended Jeremy Clarkson's Top Gear run

Jeremy Clarkson's long run as a Top Gear host has come to an end, and the reason is clear: His physical assault on one of the show's producers crossed a line, and the government-owned BBC couldn't tolerate it. The incident between Clarkson and Top Gear producer Oisin Tymon was initially described as a "fracas," and Clarkson was suspended. But his popularity and widespread support – even British Prime Minister David Cameron weighed in – suggested that the controversial Clarkson might be given yet another chance. The BBC put this to rest Wednesday when it sacked Clarkson and revealed the findings of its investigation. The report spelled out how Clarkson struck Tymon on the patio of a North Yorkshire (UK) hotel, leaving him with a bloodied, swollen lip. It was severe enough that the producer sought medical treatment. During and after the attack, Clarkson shouted expletives at Tymon and threatened to fire him. The noise carried into the hotel's dining room and even to a bedroom. Local police investigated the incident, but Tymon isn't pressing charges. The huge audience numbers, Clarkson's popularity and the high-octane excitement of Top Gear all melted away in the eyes of BBC director-general Tony Hall, who saw an attacker and a victim. "For me a line has been crossed," he said in a statement. "There cannot be one rule for one and one rule for another dictated by either rank, or public relations and commercial considerations." In that moment, Clarkson was the bad guy, though he was actually the one who reported it to the network and made repeated attempts to apologize to Tymon. He's also urged the media to leave the producer alone. Hall voiced regret in the statement that announced Clarkson's contract would not be renewed, but the BBC decided to move on. Rumors are swirling about possible replacements for Clarkson. The network says it wants to continue Top Gear in 2016 and is looking to air the rest of this season's episodes. Despite the controversy, the show has a global audience of 350 million viewers and is one of the BBC's most valuable properties. It's unclear what Clarkson's co-hosts, James May and Richard Hammond, will do, as their contracts were also reportedly up to be renewed. Other News & Notes 2016 Chevrolet Malibu hybrid charges up with Volt technology Chevrolet is taking some of the learnings and technologies from the 2016 Volt and dropping them into the reborn Malibu hybrid.

Is the skill of rev matching being lost to computers?

If the ability to drive a vehicle equipped with a manual gearbox is becoming a lost art, then the skill of being able to match revs on downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. The usefulness of rev matching in street driving is limited most of the time – aside from sounding cool and impressing your friends. But out on a race track or the occasional fast, windy road, its benefits are abundantly clear. While in motion, the engine speed and wheel speed of a vehicle with a manual transmission are kept in sync when the clutch is engaged (i.e. when the clutch pedal is not being pressed down). However, when changing gear, that mechanical link is severed briefly, and the synchronization between the motor and wheels is broken. When upshifting during acceleration, this isn't much of an issue, as there's typically not a huge disparity between engine speed and wheel speed as a car accelerates. Rev-matching downshifts is the stuff they would teach at the automotive equivalent of the Shaolin Temple. But when slowing down and downshifting – as you might do when approaching a corner at a high rate of speed – that gap of time caused by the disengagement of the clutch from the engine causes the revs to drop. Without bringing up the revs somehow to help the engine speed match the wheel speed in the gear you're about to use, you'll typically get a sudden jolt when re-engaging the clutch as physics brings everything back into sync. That jolt can be a big problem when you're moving along swiftly, causing instability or even a loss of traction, particularly in rear-wheel-drive cars. So the point of rev matching is to blip the throttle simultaneously as you downshift gears in order to bring the engine speed to a closer match with the wheel speed before you re-engage the clutch in that lower gear, in turn providing a much smoother downshift. When braking is thrown in, you get heel-toe downshifting, which involves some dexterity to use all three pedals at the same time with just two feet – clutch in, slow the car while revving, clutch out. However, even if you're aware of heel-toe technique and the basic elements of how to perform a rev match, perfecting it to the point of making it useful can be difficult.