2009 Infiniti G37X Sport (Photo copyright 2009 Dan Roth... 2009 Infiniti G37X Sport (Photo copyright 2009 Dan Roth / Weblogs, Inc.).

"Being close" matters with horseshoes, hand grenades and misguided arithmetic. In past years, the Infiniti G sedan has been close, but compared to the Kaiser of the Klasse, BMW's 3 Series, the G35 was near the stake, but not a ringer. "Almost as good," we'd all nod, "but its biggest strength is that it's a bargain."

When the G37 arrived, our initial thought was it was simply an amplified G35, a car that's delighted our socks off in the past. But same car, bigger engine isn't the whole of the story. Just as gourmet chefs tinker with recipes, Infiniti has made adjustments. Embracing the spirit of Kaizen, Infiniti refuses to leave well enough alone, and the G37XS doesn't need to trade as heavily on its value proposition anymore. The G line has always driven well, but there's always been compromise, too. Cheap interiors, choppy ride – a history of "not quite." Has the G improved to the point of full greatness? And what happens when you add all-wheel drive to the mix? We hit the road to find out.

This car's suit of armor was new with the V36 version of the G, and it's already very subtly changed for 2009 (it's due to undergo another transformation next week). A different front airdam is the most noticeable modification, but only ADHD kids loaded to the teeth with Ritalin would notice. G35 owners might appreciate the continuity of form, and it's a shape that doesn't have any major flaws. It's less outr?em> than some of its segment-mates, but still modern, attractive and un-vanilla. The line down the flanks breaks light cleanly over the G37's surface, and the sculpting of the hood still hints at pontoon fenders, just as it did on the G35 back in 2007. Our test model wore its Moonlight White, sport-package wheels and trunk spoiler well, coming across as simultaneously sporty and sophisticated.

When the G35 debuted on Nissan's FM platform, its interior was nearly Nineties Sentra-grade. The major rework in 2007 saw a massive upgrade to a class-competitive cabin which has been further augmented in the G37. The fancy-feeling metallic trim with washi-paper finish is classy, and the materials and fit and finish are finally up to snuff. The door panels are newly adorned with soft touch material this year, too.

The G37 makes you feel less cheated if you skip the navigation system by still coddling you in relative luxury with a seven-inch LCD screen that glares uselessly back like HAL 9000's red eye. Tan leather (Infiniti says Wheat) coats the G37's fantastic seats (really, all cars should come with an extendable lower cushion for extra thigh support) and made our G light and airy. Bright surfaces do require more fastidious cleaning, so you might want to go darker if your Newfoundland rides shotgun.

Front thrones that make 1,000-mile days seem exciting are a high point for the G37, and Infiniti has gotten most of the ergonomics right. The interface for the navigation and other tech features combines an iDrive-like wheely/buttony thing with a touchscreen, which we figured out after we spent an hour swearing at the thing. The small "back" button to the lower left also made life easier once we found it. The G37 brings redesigned seat heater switches and a Bose "Studio on Wheels" that marks the first time a digital-to-analog microchip is being touted as a selling feature – one of the only Bose systems we've been impressed with in recent memory.

The powertrain is where the real metamorphosis has occurred. Nissan's lauded VQ V6, a superhero of workaday engines, has bulked up to 3.7 liters. Now good for 328 horsepower, this versatile and long-serving engine continues to be incredible after this thorough reworking has added deck height to the block for more stroke. It's relatively big, but won't hesitate to zing its pistons into a frothy steeplechase for the top of the tachometer. Power is strong everywhere, and it shoves the G around with far more authority than its 269 pound-feet of torque would indicate. There's a particularly muscular rush from 2,500 rpm onward thanks to VVEL variable valve timing and lift. Though there have been complaints lodged against the VQ's aural quality, we suspect those whiners are likely overly enamored with the classic V8 rhythm. This thing barks with authority and sounds great, especially tearing toward its 7,600 rpm redline. We spent enough time cracking the drive-by-wire throttles open that we saw 20 mpg, easily within the 18/25 range the EPA says to expect.

Along with the bigger lungs, the G37 picks up an extra ratio for its automatic transmission, now up to seven. The ballet of clutch/throttle/shifter is still served by the available six-speed manual transmission, but the auto 'box not only refines the G, it's got an extra gear to play with, subsequently changing the character of the car. The manual is better in theory than in execution; the clutch is a vague, frustrating thing. In contrast, the seven-speed automatic is smooth and quick, delivering precise changes devoid of the hunting and pecking found on some of the competition. Shift paddles rendered in magnesium are there for those who want to play, as well as a gate for sport/manual mode. Not all cars with manual-gated automatics are successful, but the G37 pulls it off by being responsive and obedient, with rev-matching downshifts for an added bit of balance and excitement.

With more engine-room oomph, there comes a time when kinetic energy must be converted to heat. A revised braking system is standard on Sport models with four-piston front calipers and two piston rears augmented by gizmos like brake force distribution, brake assist and preview braking that gives the binders a shot of adrenaline in panic stops. We either never had to call on these technology to save our skins, or the systems are totally transparent in operation. The power steering system also twiddles with weighting in deference to the vehicle's speed. At times it can feel too light and it's not quite as pure and direct as you'll find in the famous Germans, but you'd never know it by the way we were grinning as we tore off in search of another apex. Some of the steering feel dilution may boil down to the all-wheel-drive nature of the G37X we drove, but any disconnection at the helm is made up for with the additional front grip.

The ride and handling balance is what's always been difficult for challengers to match compared to the established champions. Infiniti has achieved a nearly perfect supple but sporty alchemy in the G37. Occasions of harshness are very rare, and the G is quiet and restrained until its time to bare fangs. The exhaust note is also an ever-present reminder of the sports car platform underneath. The chassis is controlled and athletic; Infiniti has been hitting the books, and now the understudy knows all the lead's lines by heart.

The G37 may be the point where Infiniti's upstart challenge comes fully into its own. All of the qualifiers used on earlier Gs have been erased. The G37 is as serious as those with which it intends to compete. It's got a sumptuous interior as standard equipment, its performance is truly that of a sports car wrapped in sedan bodywork, and the changes wrought with the larger engine and extra shiftability give the G37 a sheen of refinement. Considering the $43,000 price of our well-equipped G37XS, you're never going to miss whatever je ne sais quois you think might be baked in to cars from The Continent, and yes, the G37 is still a far better deal.

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