The engine may be the same displacement and configuration, but it's far from merely a mildly tweaked carryover from the 2006 G35. By way of emphasis, Infiniti says some 80 percent of the engine's major components have been redesigned. Variable exhaust valve timing has been added, for example. A beefier engine block, modified pistons and, of course, new coding in the engine management computer have endowed the engine with a higher rev limit, now 7500 revolutions per minute versus last year's 6600 rpm. These modifications, together with a higher compression ratio (10.6:1 vs. 10.3:1), additional knock sensors, improved cooling, Iridium spark plugs and a freer flowing intake and exhaust system, not only boost the horsepower but also are supposed to deliver that added power more smoothly and over a broader power curve.

It works. Where last year's engine seemed to run out of breath, so to speak, as it neared its red line, the '07's pulls right up to its maximum rpm. It willingly and heartily revs to levels normally associated with smaller, less complex engines, along the lines, say, of the 2.2-liter, four-cylinder screamer that powers the Honda S2000 sports car. Fuel economy is up, too, by one mile per gallon in both city and highway driving, according to EPA estimates. That said, the new G35 still trails the 2006 BMW 330i and Lexus IS 350 by as much as 2 mpg in city and highway driving.

The transmissions ably handle the engine's power and power curve. Clutch operation on the six-speed manual is heavier than we would expect on a sedan, even a sports sedan. This makes for sometimes rocky clutch engagement, especially at low speeds and light throttle. A luxury car's shift lever ought not vibrate as much as the one in the pre-sale test car, but Infiniti techies said this was an anomaly that will be cured in cars built for sale to consumers. Similar assurances were given for a whine in the first four gears that evoked memories of straight-cut gears in full-on race cars. Shift pattern and gear selection, though, were tight and precise, respectively, requiring little effort.

The automatic does its job rather casually at part throttle. Holding the right foot unwaveringly hard to the floor produced sharper, more solid shifts at the engine's redline. The automatic changes gears the quickest and, interestingly, the smoothest with either the shift lever or the column-mounted paddles and under full throttle; it's like a power shift but without the clutch. Credit this to the engine's electronics, which feather the throttle through the instantaneous shift. The same electronics deliver smooth downshifts, too, whether in full auto mode or manual override, by blipping the throttle to match engine rpm to transmission speed in the lower gear; think double clutching a pure, manual gearbox.

Ride and handling are consistent across the line with the notable and commendable exception of the Sport models with four-wheel steer. Besides actively adjusting the rear wheel toe by up to a degree depending on vehicle speed and steering angle, that option brings with it a sportier shock and spring setup and road speed-sensitive, variable ratio power steering. For hustling down winding roads, this suspension and 4WS combination is the preferred. And it's not all that far out of its element cruising the Interstate. It's solid and taut and manages the G35's mass very well without exacting a price in stiffness. It's firm, yes, and will transmit pavement heaves more dramatically into the passenger compartment. But over anything less than chunking blacktop or weathered concrete, it gives up very little against the standard suspension, which leans a bit more toward supple. Not that the base suspension is floaty by any means, far from it, actually. But as demonstrated over several, fairly hot laps on a racetrack, it's not as planted and controlled as the 4WS Sport.

At that racetrack, Infiniti made available for comparison a BMW 330i and Lexus IS 350 (both 2006 models). While time spent behind the wheel of the G35 sedans and the BMW and the Lexus, or any car, for that matter, on a racetrack has limited relevance to everyday street driving, it nevertheless revealed some significant distinctions. Power differences were obvious, of course, with the BMW (255 hp, 220 lb.-ft. of torque) lagging the IS 350 (306 hp, 277 lb.-ft. of torque) and the '07 G35 in outright acceleration (the curb weights for all three fall within a 75-lb. range).

In cornering, the IS 350 understeered (where the car doesn't want to turn as much as the driver wants) the earliest and the most, with the G35 next and the BMW nearest to neutral. This last isn't necessarily surprising, as the BMW's front/rear weight distribution is 51 percent/49 percent, very close to the 50/50 balance most suspension designers consider ideal for handling responsiveness, while the split on the Lexus is 52/48. What's telling here is that the G35's front/rear distribution is 53/47, but its aggressive suspension geometry and tuning compensate for the greater front-end bias. Even better, with 4WS, which gives the rear tires a gentle nudge in the same direction as the driver is turning the steering wheel, the G35 cornered almost as predictably and precisely as the BMW. It also tracked with greater certainty, and with substantially less excitement, when the car's suspension unloaded over a slight rise in the track at the exit of a high-speed, uphill sweeper.quietly. Gone is the irritating drone that often plagued rear seat passengers in '06 G35 sedans. There's little wind noise even at extra-legal speeds. There's more road noise from optional tire package than from the standard treads, but the added grip and, frankly, sharper looking 18-inch wheels are worth it