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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.

Nissan Leaf sells 1,553 in April, Volt climbs to 905

After three months in the 500 and 600 range, sales of the Chevy Volt climbed to 905 in April. That's up for the year so far – likely due to increasing discounts – but still down 41.5 percent from April 2014. As we've been saying every time the Volt turns in less-than-exciting monthly sales numbers, we suspect a large number of potential Volt buyers are waiting for the next-gen model to arrive in the second half of 2015. While the price for that car has not yet been announced, the updated tech specs show that it will probably be worth the wait for drivers who want the latest and greatest. Over on the Nissan Leaf side of things, April sales were 1,553 units this year. That's the second-best month of the year but down from the 2,088 units sold last April. After the Leaf finally climbed to the top of the cumulative best sellers list for plug-in vehicles last month, the difference between these two leaders is now 1,824 in favor of the Leaf. Nissan says that sales were influenced by the launch of its No Charge To Charge promotion in Indianapolis and Fresno, CA. This deal gives new Leaf buyers and lessees two years of no-cost quick charging in these markets. No Charge To Charge is not available in 15 US markets for (San Francisco, Sacramento, San Diego, Seattle, Portland, Nashville, Phoenix, Dallas-Ft. Worth, Houston, Washington, DC, Los Angeles, Chicago and Atlanta) and will expand to 10 more by the middle of this year. As we do every month, our full wrap-up of US green car sales is coming soon. For now, enjoy discussing these sales figures in the Comments below.

Ford Mustang chief engineer, mid-engine Corvette | Autoblog Podcast #488

Note: There were some technical difficulties that prevented some of you from downloading this week's podcast. The player and link below should be working now, and the file has reached iTunes and other feeds as well. Thanks to everyone who wrote in to let us know of the issues! On the podcast this week, we have some questions for Ford Chief Engineer Carl Widman. Plus, Associate Editor Reese Counts joins Mike Austin to talk about the latest news, most notably the spy photos of the upcoming mid-engine Corvette. We also chat about the Jaguar F-Type Coupe, the Nissan Armada, and why 0-60 mph is a stupid performance figure. And, of course, we get into some Spend My Money advice, telling strangers what car to buy. And new this week is a cost-no-object what-cars-would-you-buy game. The rundown is below. And don't forget to send us your questions, money-spend or otherwise, to podcast at autoblog dot com. Autoblog Podcast #488 The video meant to be presented here is no longer available. Sorry for the inconvenience. Topics and stories we mention Mid-engine Chevrolet Corvette spied Chevy Bolt EV comes with 238 miles of range Ford will sell self-driving cars by 2025 Jaguar F-Type Coupe 2017 Nissan Armada (yes, Mike knows it's not a Patrol) Ford Mustang Chief Engineer Carl Widman interview Spend My Money - we give purchase advice Why 0–60 mph is a stupid performance test Rundown Intro - 00:00 The news - 03:30 What we've been driving - 16:20 Carl Widman - 26:44 Spend my money - 37:03 New fun game - 51:48 0–60 mph is overrated - 56:50 Total Duration: 1:04:57 Get The Podcast iTunes – Subscribe to the Autoblog Podcast in iTunes RSS – Add the Autoblog Podcast feed to your RSS aggregator MP3 – Download the MP3 directly Feedback Email – Podcast at Autoblog dot com Review the show in iTunes Podcasts Chevrolet Ford Jaguar Nissan Car Buying nissan armada mid-engine corvette jaguar f-type coupe