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Infiniti's new VC-T changes the rules of small turbocharged engines

The upcoming Infiniti QX50 crossover does not get our pulse racing, no matter how shapely the QX Sport Inspiration concept that previews it may be. No midsize SUV does, to be fair. But it has something special under the hood – the world's first production variable-compression-ratio engine. That means the QX50's 2.0-liter turbo four, which makes 268 horsepower and 288 pound-feet of torque, will have up to 27 percent better fuel economy. Here's how it works. The trend of moving to smaller, turbocharged engines carries with it one big falsehood. Under low load when the turbo isn't needed, these engines are less efficient than an equivalent engine without a turbo because of the low compression ratio the turbo requires. That is, if you never need the extra power, you're wasting fuel. Turbocharged (and supercharged) engines use a lower compression ratio to prevent detonation. When you force extra air in a cylinder and mix it with fuel, it's more likely to prematurely go boom. Lowering the compression ratio prevents this problem, but it's less efficient. Infiniti's VC-T promises the best of both worlds, with a compression ratio that ranges from 8.0:1 for high-power turbo needs to a 14.0:1 ratio for fuel-sipping efficiency. At its heart the VC-T engine is a simple idea, but it's complicated to explain. Consider yourself warned. The photo below from Infiniti serves as a good visual overview. For the truly nerdy, this patent application covers the mechanical concept. Instead of having the pistons connected to the crankshaft, Infiniti's engine has a pivot arm with a connection on each end. One end connects to the piston, the other connects to a second lower shaft, which is controlled by an actuator arm. At any given time the engine's pistons move up and down according to the lobes on the crankshaft. But the actuator arm can change the angle of the pivot arm up and down. That is, the pistons still move in the same motion with the same stroke, but phase the entire stroke up or down. Move the pivot up and there's less room at the top, which means a higher compression ratio. Move the pivot down and the compression ratio goes down, too. As an added bonus, the lower shaft eliminates the need for counter-rotating balance shafts. Infiniti says this system works constantly and can vary the compression ratio to any number between 8:1 and 14:1. It also uses electronic variable valve timing on the intake valves to switch into Atkinson-cycle combustion for greater efficiency.

Tesla leads and Infiniti bleeds in Consumer Reports' satisfaction survey

According to Consumer Reports, Tesla owners are more likely to rave about their vehicles than any other brand. And we're not surprised — Tesla has performed very well in past customer satisfaction surveys, despite the fact that the electric cars themselves tend to have more problems than most other automobiles. Second place went to Lincoln, which interestingly had a higher cumulative score than Tesla in individual category measurements like comfort and storage space. Ram, a truck-only brand, rounded out the top three. The consumer-focused magazine bases its owner satisfaction score on responses to a very simple question: Would you buy this exact car again? The higher percentage of owners who answer "definitely yes" to that question, the higher the satisfaction score. Further breakdowns are scored for other parts of the ownership experience, which is why brands that rank poorly in Consumer Reports' own reliability charts — like Tesla and Lincoln, for example — can still earn top marks for satisfaction. The lowest-ranked brands for satisfaction are Cadillac, Nissan and Infiniti. Interestingly, Cadillac performed better than average in Driving and Comfort and middle-of-the-road in the In-Car Electronics and Cabin Storage, but like most other brands, scored poorly in Value. In fact, only Subaru, Mazda and Volkswagen scored better than average in Value. Nissan and especially Infiniti earned comparatively low marks across the board to go along with the bottom-of-the-barrel satisfaction score. Here's the full list of automakers from Consumer Reports' satisfaction survey, ranked in order from best to worst: Tesla Lincoln Ram Chrysler Subaru Hyundai Porsche Dodge Mazda Toyota Kia Mini BMW Ford Audi Honda Volvo Volkswagen Lexus Jeep GMC Chevrolet Mercedes-Benz Buick Cadillac Nissan Infiniti It's worth diving into the individual category scores in addition to the official finishing order for a full look at the results. For instance, despite the fact that automakers like Lincoln and Ford use similar infotainment systems, their In-Car Electronics scores don't quite match up. Also, some automakers have full lineups with multiple cars, trucks and SUVs while others offer just a couple of nameplates. Head on over to Consumer Reports for all the details. Looking for a reliable car, truck or SUV? Check out the top 10 vehicles that owners keep the longest.

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.