After driving the 2007 BMW 335i and 2008 Infiniti G37, we wonder if the people who built them thought about anything besides going fast.

Between the twin turbochargers nesting on the 335i's inline six-cylinder and the large-displacement V6 that gives the G37 its name, we're waist-deep in a level of engine might that recalls an E46 BMW M3 — and we've scarcely passed the $40,000 price barrier.

The 2007 BMW 335i and 2008 Infiniti G37 coupes make you see the idea of a four-passenger, rear-drive luxury coupe in a new way. It still needs to be attractive, elegant and graceful. Handling still ought to be sharp, balanced and involving. But raw speed has become an important measure of worth. A snarky exhaust is now a sign of virtue.

The Gap Narrows
As you'd guess from the Sport suffix, a sport package is standard on this flavor of G. In addition to the expected firmer suspension settings and sport seats, it supplies a limited-slip differential, 19-inch wheels with Bridgestone Potenza RE050A tires, and larger-diameter brake discs at all four corners. With a six-speed manual gearbox, the price of the G37 Sport starts out just under $36,000, Infiniti tells us. (Infiniti has yet to release official pricing for the 2008 G37.)

Our test car had nearly the full load of options, however. Big-ticket items included a hard-drive-based navigation system, Infiniti's new Four-Wheel Active Steer (4WAS) and the Premium Package, which provides high-end Bose sound, a sunroof, Bluetooth and all sorts of cabin conveniences. With an additional $550 for a spoiler, we estimate the total bill at $42,413.

From there it's only a $3,800 jump to our 2007 BMW 335i test car, also a six-speed manual. It was a conventionally equipped 3 Series coupe, meaning it had both the Sport and Premium Packages but no navigation system (and therefore no iDrive).

The BMW's Sport upgrades consist of 18-inch wheels, a run-flat set of Bridgestone Potenza RE050As and generously bolstered seats. The Premium group adds leather, Bluetooth, BMW Assist telematics and various conveniences. Active steering is available, but our test car didn't have it. Heated seats ($500) and Sparkling Graphite paint ($475) were additional line items, yielding an MSRP of $46,200.

Infiniti G37: Going for Exotic Character
Though the G37 seems more like a 3 Series than ever when you look at its price and equipment, it feels pretty exotic when you settle into the driver seat.

The seat is mounted as low as the beltline is high, and you're gently coaxed into adopting a reclined driving position, as if you were driving a Formula 1 car. The control layout is ergonomically superb. The seat is a tad squishy, but it envelops your body and even offers a seat-bottom cushion that you can extend to support your legs — you know, like in a BMW.

As you look out through the dramatically sloped windshield, you'd swear you were looking into a Ferrari's cleavage, as the curves of the G's front quarter-panel curves rise softly to frame the oncoming blacktop.

Powerful but Conflicted
Setting out, the Infiniti G37 is at once relaxed and frenetic. Rated for 330 horsepower at 7,000 rpm and 270 pound-feet of torque at 5,200 rpm, the new 3.7-liter V6 delivers useful wallop off the line, but like the 3.5 before it, this engine prefers to do business in the midrange of its power band.

Shifting the six-speed box is not as pleasurable as it should be, either. The weighty clutch engages without subtlety, as if to say, "Get it over with, tenderfoot." But the shift action isn't as decisive. The shift lever is a nice piece in your hand (especially since it doesn't resonate with engine vibration, as it did in the G35 sedan), but it navigates slowly if precisely through the gates, as if it needs to carefully digest all that engine power.

At the test track, this drivetrain delivers the G37 to the quarter-mile mark in 13.8 seconds at 102 mph, while a run to 60 mph takes 5.4 seconds.

Unrealized Potential
Around town, the Infiniti coupe's stiff chassis reminds you that every second you waste running errands in suburbia could be better spent on a remote back road. Surprisingly, this tautly calibrated chassis proved compliant over most pavement surfaces.

Once on the back roads, the Infiniti G37 isn't as hard-core as its tightly wound chassis would have you believe. It carries a flat attitude through corners, but it's never truly eager to change direction. The brake pedal feels vague and hard to modulate. Most of all, the steering doesn't weight up properly, and the feedback only comes through at a trickle.

In light of our more positive experience with an automatic 2008 G37 coupe, we blame the 4WAS system that is a mandatory addition to the equipment list of the G37 Sport with a six-speed manual transmission. The 4WAS attempts to vary the steering ratio between 12:1 and 20:1, and swivels the rear wheels up to 1 degree in line with the fronts. All this contributes to the G37 coupe's high-speed stability but seems to reduce the car's appetite for corners.

In the more controlled environment of our instrumented testing facility, 4WAS doesn't seem to hamper the G37, and the car maintains 71.3 mph through the slalom. The supersize brakes are not quite up to their promise, as the 3,715-pound G37 stops in 115 feet from 60 mph on its first run, but fades to 122 feet by the fifth run.

3 Series Coupe: Return to the Conventional
The 335i coupe feels like a sedan once you get behind the wheel. The seating position is higher, the cowl is lower and visibility is excellent in all directions.

The BMW has firmer seat cushions than the Infiniti, too. There's the manually adjustable bottom cushion that you expect in a BMW, plus the seatback's side bolsters can be adjusted to give you a tighter squeeze as well. And there's plenty of headroom, something that can't be said of the sunroof-equipped G37 coupe.

You won't get any thrilling views of the 335i's sheet metal through the windshield, however. This car is too down-to-business to allow such indiscretions.

Indiscreet Grunt
Indecency surfaces elsewhere. The amount of torque juicing the BMW's wide 255/35R18 rear tires might be deemed such. So might the manly exhaust roar.

But you'd forgive this twin-turbo, direct-injected 3.0-liter six almost anything and not just because of its impressive ratings of 300 hp at 5,800 rpm and 300 lb-ft of torque at an incredibly modest 1,400 rpm. Rather, it's that numerical potency combined with the engine's extreme tractability. This turbo inline-6 is smoother than the G37's V6. And as free-revving as the Nissan VQ V6 is, this twin-turbo six likes to rev even more.

As with all Bimmer gearboxes, this one feels slightly glutinous as you move the lever through the gates. Compared to the G's shift action, though, the BMW has a lighter-effort feel and it snaps positively into gear. The 335i's clutch engagement is also smoother and more predictable than that of the G37.

These impressions were borne out at the test track, where the 335i was not only four-tenths of a second quicker to the quarter-mile mark with a 13.4-second run but also moving at a significantly faster clip of 104.3 mph. Meanwhile, 60 mph came up in just 4.8 seconds.

All the Necessary Details
Our test-driving loops on back roads also revealed the 2007 BMW 335i to be faster in real-world driving, even though its softer suspension tune compromised our slalom testing, where the BMW recorded 69.5 mph. Feedback is what makes the difference. Both coupes talk to their drivers, but the 335i speaks in great detail.

We're so locked into the car's progress down the road through the compliant chassis and textured steering, we push on without reservation. Although the BMW's steering ratio of 16.0:1 suggests otherwise, the 3 Series reacts to its steering more quickly than the G37.

Once you get deep into the BMW's middle pedal, it's easy to get the full measure of the brakes. At the track, our 3,542-pound 335i test car came to a halt in 109 feet and never deviated more than a foot over our series of stops.

The BMW held only a surprisingly slim advantage in ride comfort over the Infiniti, perhaps because of the 335i's run-flat tires.

The Dyno Beckons
Although our 3,715-pound Infiniti G37 test car weighed in almost 200 pounds heavier than our 3,542-pound BMW 335i coupe, we puzzled over the wide difference in their respective acceleration performance and the G's relative lack of high-rpm vigor. The Infiniti is supposed to have a 30-hp advantage, but it wasn't adding up.

This led us back to the chassis dynamometer at MD Automotive in Westminster, California, the same facility we used to test an overachieving, automatic-equipped 335i.

As the dyno reveals, our 335i test car produces 280 hp 5,800 rpm as measured at the rear wheels, while the G37 comes up with 281 hp at 7,200 rpm. As close as these numbers look, the 335i holds a huge advantage over the G in power under the curve from idle to 6,350 rpm. And if you look at torque, the difference is even uglier: 279 lb-ft at 3,370 rpm for the BMW versus 229 at 4,500 rpm for the Infiniti.

The thing to keep in mind is that the G37's dyno numbers are actually right on target. They're 15 percent lower than the published specifications (which don't take drivetrain losses into account) and that's what you can expect from most production cars. The 335i's numbers were only 7 percent down from the specs, which suggest to us that BMW has slightly underrated it.

The Rest of the Time
So the BMW 335i is the better drive, but would you want to live with it? It depends on your priorities. If the latest technology is a must-have for you, the Infiniti G37 is the better choice. In addition to giving you more content per dollar, the G has a more ergonomically sound layout for the controls, as reflected in its excellent navigation system that deftly blends touchscreen and directional-button functionality.

If quality and interior passenger volume matter to you, the BMW is the one you want. True, you pay extra to get leather in the Bimmer, but the standard hides in the G feel like they belong in a $30,000 car, not a $40,000 one.

We were also surprised to find the BMW has 88.5 cubic feet of passenger volume, while the G37 is rated at 85.0 cubic feet (82.7 when a sunroof is present).

Deceptively Close
Whether you consider this battle a pedigreed recasting of the Camaro-Mustang rivalry or a superficial spat to be had between handsomely paid professionals, one thing's certain: Neither coupe would have gotten this much engine if the other didn't exist.

Very likely, they wouldn't stop or handle as well, either. Nor would they each offer an active steering system as an option. At heart, the 2007 BMW 335i and 2008 Infiniti G37 are chasing the same driver.

And by most standards, the Infiniti G37 is an impressive car and a lot of fun. But it isn't as quick as the BMW 335i, nor does it engage its driver with equal commitment.

Due to its higher price and shorter features list, the 3 Series won this test by only 2.3 points. But contained within those points are all the details that make it a more intimate and involving driving partner.

"Nearly every aspect of our drive feels more natural in the 335i," one of our editors recorded in the notebook for this comparison. "I'm not sure what the price difference is, but the BMW feels $15,000 better."