2012 Nissan Altima 2.5 S Sedan Automatic Cruise Ctl 37k Texas Direct Auto on 2040-cars

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Roller coaster or racecar, which pulls more Gs?

Looking for a thrill? You're not the only one. You'll find kindred spirits at airfields going up for a skydive, atop bridges and towers with bungees attached to their feet and standing in line for roller coasters at the local amusement park. But you'll also find them in the paddock at the racing circuit.
So what's the commonality? G-force. It's like gravity, only in each of these cases, it's experienced by human invention. But which activity subjects your body to the greatest amount of g-force? That's what Nissan set to find out.
Before putting them back in the cockpit, Nismo sent out two of its young hot-shoes - Jann Mardenborough and Mark Shulzhitskiy - to an amusement park in the UK with a camera and a g-force meter to find out if any of the coasters could produce as much lateral gravitational force as an LMP2 racing car. See what they found in the pair of videos, below.

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.

DC fast charging not as damaging to EV batteries as expected

As convenient as DC fast charging is, there have been lots of warnings that repeated dumping of so many electrons into an electric vehicle's battery pack in such a short time would reduce the battery's life. While everyone agrees that DC fast charging does have some effect on battery life, it may not be as bad as previously expected. Over on SimanaitisSays, Dennis Simanaitis, writes about a recent presentation by Matt Shirk of the Idaho National Laboratory (INL) called DC Fast, Wireless, And Conductive Charging Evaluation Projects (PDF) that describes an ongoing test of four 2012 Nissan Leaf EVs that are being charged in two pairs of two. One pair only recharges from 50-kW DC fast chargers, which the other two sip from 3.3-kW Level 2 chargers exclusively. Otherwise, the cars are operated pretty much the same: climate is automatically set to 72 degrees, are driven on public roads around Phoenix, AZ and have the same set of dedicated drivers is rotated through the four cars. "Degradation depends more on the miles traveled than on the nature of recharging." What's most interesting are the charts on page seven of Shirk's presentation (click the image above to enlarge), which show the energy capacity of each of the four vehicles. When they were new, the four batteries were each tested to measure their energy capacity and given a 0 capacity loss baseline. They were then tested at 10,000, 20,000, 30,000 and 40,000 miles, and at each point, the DC-only EVs had roughly the same amount of battery loss as the Level 2 test subjects. The DC cars did lose a bit more at each test, but only around a 25-percent overall loss after 40k, compared to 23 percent for the Level 2 cars. Simanaitis' takeaway is that, "INL data suggest that the amount of degradation depends more on the miles traveled than on the nature of recharging." The tests are part of the INLs' Advanced Vehicle Testing Activity work and a final report is forthcoming. These initial numbers from IPL do mesh with other research into DC fast charging, though. Mitsubishi said daily fast charging wouldn't really hurt the battery in the i-MiEV and MIT tests of a Fisker Karma battery showed just 10-percent loss over 1,500 rapid charge-discharge cycles.