Sporty handling and a willing engine make the Infiniti G models exhilarating to drive. Relative archrival Lexus, the G maintains Infiniti's stance a car is first and foremost to be driven. And a G with a Sport or IPL package has a performance edge, a rawness, that sets it apart.
Where the G has come up short is in the smoothness, finish and refinement of a luxury car. To Infiniti's credit, it has incrementally but steadily addressed the problem, to the point where the G line stands on better footing, perhaps not quite Lexus levels of quietness but competitive.
The newest G and arguably the best value is the G25. It uses a smaller and smoother 2.5-liter V6 engine to lower the price and weight, increase the fuel economy, take some weight off the nose for crisper steering input and for most North American drivers on U.S. roads the 218 horsepower will be more than sufficient. The G25 7-speed automatic has closer gear ratios than in G37 automatics to get the best out of the smaller 2.5-liter engine. We had no trouble passing slower traffic or merging on the fastest expressways in the G25. By virtue of its smaller dimensions the engine is smoother than the big V6 in G37s, and while the Lexus IS250 is more refined, it doesn't seem as sporty as the G25.
On the open road the G cruises comfortably, quietly and so stable that little driver input for steering correction is ever needed. The suspension is taut and compliant, not nearly as soft as many mid-luxury models, and even the sport package is forgiving enough to drive daily. Only big, sharp bumps transmit any ruckus to the cabin, which is magnified on sport packages because of the lower profile tires, but that might help you avoid ruining them on potholes.
There's little wind noise even at extra-legal speeds. There's more road noise from the larger tire packages than from the standard treads. However, we preferred the added grip and sharper looking appearance of the 19-inch wheels; even with tire replacement costs figured in, we think they're worth the extra cost.
All G37 models are equipped with the same 3.7-liter V6, though the output varies from 325-348 hp. These engines are not turbocharged so they make their best power at higher revs, and they're big enough that midrange is more than sufficient to get the job done briskly. Though they rev to 7500 rpm, they are not as smooth about it as the earlier 3.5-liter.
In a 3700-pound car, 330 horsepower delivers strong acceleration. Stand on the gas and the 3.7-liter V6 willingly and heartily rev to levels normally associated with smaller, less complex engines, right up to maximum rpm. And the character is as important as sheer performance. In contrast, BMW's turbo 3-liter brings 300-plus horsepower and better torque for urban drivability, Audi's 2-liter turbo makes almost as much torque but not the revving horsepower, and Lexus' and Acura's 3.5-3.7 liter V6s deliver 300-306 hp, with torque similar to the G37's.
The 7-speed automatic transmission enables hard acceleration, with two overdrives for more relaxed highway cruising. It does its job casually at part-throttle and briskly when you're in a hurry. If the driver moves the stubby leather-wrapped shift lever to the left, however, Sport mode is engaged. The upshifts come at higher rpm, upshifts and downshifts are quicker, it rev-matches downshifts, and it downshifts automatically under moderate-to-heavy braking.
We got good seat time in a Graphite Shadow IPL coupe with Monaco red leather interior, and loved every minute. You know you're in a sports car. We can't wait for the IPL convertible, coming soon, because the IPL feels like it wants to be free like a sports car. It feels like a gentleman's 370Z, even with an automatic transmission, because the 7-speed manual automatic with beautiful magnesium paddle shifters is worthy. Its programming is true.
The exhaust system of the IPL has been loosened up, and the electronics have been retuned to raise horsepower to 348. No way would we scoff at that number, but BMW might, with 414 horsepower in the M3, and Cadillac sure would, with 556 horsepower in the supercharged CTS-V. But both those cars are more expensive, and with the big Caddy, we might be comparing oranges to grapefruits.
Where the IPL feels small compared to super coupes is in its torque, 276 foot-pounds, peaking at 5200 rpm. In some ways, often fun ways, the engine feels like a Japanese sport bike. It makes its full horsepower up there at a screaming 7400 rpm, and with the high torque peak, the engine loves to be kept screaming. And doesn't love to be asked to lug.
In any event, you know you've got hot acceleration under the hood, with a 0-60 mph time in the low 5-second range, which is a couple tenths quicker than the G37. Power is delivered to the rear wheels via a viscous limited-slip differential.
The exhaust note is a distinctive howl from midrange up, with a deep purr at low rpm. It sounds fantastic with the engine prancing around in its loony upper octaves. But droning in traffic or loping down the highway left us wishing for a little more quiet from the vehicle's underbelly.
The brakes are massive, same as on the G37 Sport. With 14-inch rotors pressed by four-piston calipers up front and 13.8-inch discs and dual-piston calipers out back, the IPL can stand your on your forehead.
The IPL springs are firmer, for more precise handling, and it works. We ran the IPL through our favorite curves, hard as we could reasonably and safely go, and it put a smile on our face. Responsive and tight; precise turn-in, and poise in swwitchbacks. Love that rear-wheel drive.
However the ride is compromised by the firmer suspension. Despite comfortable seats, you can feel the freeway expansion joints.
We like the conventional 6-speed manual. Gear selection is precise, requiring moderate effort in keeping with the performance nature. Clutch operation is heavier than we expect in a sport coupe, heavier than in a Honda, and more in line with a V8-powered muscle car, but the engagement is easy to modulate so traffic jams aren't an unbearable nuisance. (Unlike the Z-car the G manual does not automatically blip the throttle at downshifts, which most enthusiasts switch off anyway.)
The IPL coupe is the sportiest G37, a step beyond the Sport-package coupe. Spring rates and dampers are firmed up 20 percent in front and 10 percent in the rear, while steering, tires, brakes, differential, the rest of the mechanicals, are sport-package grade. The firmer spring rates add control without making the ride feel anywhere near 20-percent harsher. We think the IPL is sufficiently compliant to serve as the standard sport package. The IPL is meant to add performance without going as far (and pricey) as BMW's M, Mercedes's AMG, or Lexus's F divisions, which they've done.
A G37 convertible feels like a sports car because of the wind in your hair and exhaust note filling your ears, but it's not as sporty in terms of outright performance as the coupe or sedan. There are two primary reasons: One, when you take the top off a car that does not have a separate frame (like some exotics) the body loses some of its stiffness, which means the suspension can't be as precisely tuned because the structure it's bolted to isn't as rigid. With the top up in a G37 convertible you'll hear this on twisting driveway entries as the roof sections move against their rubber sleeves ever so slightly, and top down, the windshield will shudder more on rough roads, an effect you can easily see by glancing at the rear view mirror.
The other reason a convertible doesn't perform as well as a coupe is weight. The power folding hardtop apparatus and the additional body framing added to improve rigidity add weight. In fact, a G37 convertible is more than 450 pounds heavier than a G37 sedan. Long before cars were around, Newton figured out the laws of equal and opposite reactions, and 4100 pounds simply doesn't change direction as quickly and easily as 3700 pounds do, all other things being equal. The G37 convertible offers the same nice steering, engine and transmissions as the coupe, but is better suited to touring than race tracks.
The front-midship layout of the G, with the engine set farther back behind the front axle, is inherently well balanced. The G has a planted, sure-footed feeling that comes from proper tuning, not extra weight or electronics masking inherent deficiencies. On any G with the Sport package, the speed-sensitive power steering is seamless. It turns precisely into corners, with no dead spots through a long curve, and is sensitive enough to feel and make very small changes.
The G37 Sport Coupe 6MT is so good it almost has a downside. Pushing harder, over remote, twisty, smooth curves, we felt the standard limited-slip differential and stability electronics (VDC) at work. Or rather, we saw the VDC working thanks to a light on the dash. The corrections are beautifully subtle. You can pitch the G37 to a ridiculous point, and the VDC just gently won't allow the car to get out of shape. It doesn't tell you how wrong you were, by cutting engine power for too long, like some electronic stability controls do.
The brakes are smooth, predictable, and the car is rock steady under heavy braking, inspiring confidence in any driver. They're also sensitive, and when you jump on them they grab, so it takes a little time to develop the technique for smooth application. The G37 Sport models come with bigger brakes than the others for less fade in repeated hard applications.
Infiniti's ATESSA E-TS all-wheel-drive system monitors data such as wheel spin, throttle position and vehicle speed, and automatically diverts up to 50 percent of the engine's power to the front wheels, improving traction and control when road conditions are less than optimal. Yet in ideal conditions, when the road is smooth and dry, the all-wheel-drive system still sends all of the power to the rear wheels, preserving the G's sporty rear-drive handling characteristics.