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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.

Renault-Nissan reportedly partnering with Waymo on self-driving cars

The Renault-Nissan-Mitsubishi alliance will tie up with Alphabet Inc's Waymo to develop autonomous taxis and other services using self-driving vehicles, the Nikkei reported on Tuesday. Google's self-driving car company Waymo will work with the carmakers and announce a plan for the arrangement as early as this spring, the business daily reported. The partners are considering the joint development of unmanned taxis using Nissan vehicles and a system that handles reservation and payments, Nikkei said. A spokesman at the Renault-Nissan-Mitsubishi alliance, Nick Twork, said, "This (Nikkei) story is based on rumors and speculation. We have nothing to announce." Waymo did not immediately reply to a request for comment. Last month, Nissan Motor Corp said its board remained committed to the carmaker's alliance with Renault SA and Mitsubishi Motors Corp, after directors met to discuss the ongoing investigation into former chairman Carlos Ghosn and ways to bolster governance. Among the companies developing autonomous driving technology, Waymo is considered to be far in the lead in terms of test-fleet miles driven. It operates hundreds of vehicles in 25 U.S. locations, and is already operating a taxi service with paying customers in Chandler, Ariz. Related Video:

Nissan may take control of struggling Mitsubishi Motors

Update: The reports were largely correct. Nissan will take a 34 percent stake in Mitsubishi for roughly $2.2b. Read all about it here. Reports say Nissan will buy a controlling stake in Mitsubishi Motors, either 30 or 34 percent, for about 200 billion yen or $1.84 billion. Nissan and Mitsubishi motors are currently part of a joint venture, NMKV, to build minicars together. Nissan is also responsible for reporting fuel-economy discrepancies with cars built under the joint-venture agreement, which put Mitsubishi in its current weakened state. Earlier today, reports surfaced that the fuel-economy issues were wider ranging than originally thought. Mitsubishi now admits that all of its Japanese-market cars sold since 1991 could have had faked fuel-economy data. Shares of Mitsubishi Motors have dropped by about half since the scandal was uncovered, opening the door for a takeover. While Nissan is a much larger company, it can benefit from Mitsubishi's 60-percent share of Japan's minicar market. The two companies also had plans to build electric vehicles together in the joint venture. Japan's Nikkei reports that talks are ongoing between the company and that a decision could be made Thursday by the companies' boards. Related Video: News Source: Nikkei Green Mitsubishi Nissan