Photo: Nissan

• Power Plant: 358-kW (480 hp) 3.8-L twin-turbocharged V6 • Transmission: Rear transaxle with sequential 6-speed; paddle shift • Claimed Fuel Efficiency: Information not available • Claimed CO2 Emissions: Information not available • More: It took the company months to decide if the US $70 000 car would be released as a Nissan or an Infiniti in the United States; in the end, it stuck with the global Nissan brand despite Infiniti's upscale image.

Possibly the world's most practical ultrahigh-performance car

The Nissan GT-R has always combined pulse-quickening performance with technological innovation. It offered all-wheel drive, four-wheel steering, and twin turbochargers many years before these features could be had in lesser vehicles. This, the fifth generation since the GT‑R's inception in 1969, is the first to be offered globally, including in the very visible U.S. market.

The car's designers have always eschewed the V8 or V12 engines used in many of its two‑seater rivals, instead using twin turbochargers to squeeze out all the power it needs from six cylinders. This year, though, they're set in “V” formation, a switch from the prior model's in‑line six. The resulting 358 kilowatts (480 horsepower) of power and 583 newton meters (437 foot‑pounds) of torque are even more impressive, considering that the car also qualifies for the ultralow-emissions vehicle rating of the U.S. Environmental Protection Agency.

The engine sits aft of the front‑wheel centers, and it drives not a conventional attached gearbox but a rear transaxle containing a dual-clutch transmission and transfer case, which then splits power among the four wheels. The dual-clutch transmission assigns separate clutches for the odd and even gears, letting it preselect the next highest and lowest gear for almost instantaneous shifts.

That unusual arrangement lets Nissan achieve a weight distribution of 53 percent front, 47 percent rear—close to the 50-50 ideal. The all-wheel drive system offers a torque split ranging smoothly from 100 percent rear to 50/50 front-rear. The driver can choose among three settings—Normal, Comfort, or R, for ultimate handling—for several systems, including engine and transmission mappings and suspension control. How often a GT‑R driver would select Comfort is moot.

Nissan says the instrument panel display is “video game–inspired,” not an unalloyed gain for those who prefer drivers to focus on driving. As is fitting in a performance car, the panel shows acceleration, brake-pedal pressure, and steering angle; it even records large blocks of operating data, like the black box on a jetliner. When not showing such data, the panel also controls the navigation system, audio equipment, and mobile phone system.

Photo: Mazda

• Power Plant: 66-kW (89 hp) 1.3-L Miller-cycle 16-valve four-cylinder • Transmission: Continuously variable transmission (CVT) • Claimed Fuel Efficiency: 4.3 L/100 km (55 mpg) on Japanese combined cycle • Claimed CO2 Emissions: 129 g/km • More: The “platform” or understructure will be the basis for a new Ford Fiesta in Europe, and Ford is considering selling it in the United States.

Newer, better equipped…and lighter

The latest Mazda2 (called the Demio in some markets) has gotten more capacious, more capable, better equipped, and at 990 kilograms, 100 kg lighter—all at the same time. With one model that offers both Mazda's Miller-cycle engine, this time in 1.3-liter form, and the company's first continuously variable transmission, it begins to look like a very advanced small car indeed.

The Miller cycle increases the efficiency of a four-cycle “Otto” engine with a fifth cycle, by dividing the compression stroke into two parts. In the first 20 to 30 percent of the stroke, the intake valves are held open so the piston can push some of the fuel-air mixture out the door, as it were. This leakage eases the load at a point when the piston's leverage is at its worst. Then the standard procedure is to push the mixture back in again using a supercharger—a compressor driven by the crankshaft—until the piston reaches a mechanically more advantageous position in which to finish the compression. Because this exploitation of mechanical advantage saves more energy than the supercharger consumes, overall efficiency improves.

Mazda, however, dispenses with the supercharger, instead minimizing the fuel-air leakage with variable valve timing and clever tweaks to the combustion chamber. The company has also minimized the lower power and torque of the Miller cycle. Compared with the conventional version of the same engine, power is down just 1 kilowatt and torque declines just slightly, to 120 from 124 newton meters (89 foot‑pounds).

Mazda says the 1.3-L Miller-cycle model uses just 4.3 liters per 100 kilometers (55 miles per gallon) in the Japanese fuel-economy cycle and cuts emissions to 75 percent below the old limits that took effect in 2005. (It is also offered with a 1.5-L engine, and a 1.4-L diesel in Europe.) The Mazda2 is not sold in the United States.

Ford is a part owner of Mazda, and so the car's design is an early indicator of one element in Ford's “blueprint for sustainability” to improve energy efficiency: make it lighter. Mazda slimmed the car down even while meeting new crash-safety standards and adding hardware, including entertainment gear and navigation systems. It did that by using ultrahigh‑strength tensile steel and stronger welds to reduce weight while improving rigidity. It also improved the coefficient of drag to 0.32, respectable for a car just 3.9 meters long but 1.5 meters high and 1.7 meters wide.