The Good: The 2012 Infiniti IPL G Coupe gets upgraded with more power, firmer suspension bits, and bigger brakes. The hard-drive-based navigation system features traffic, weather, and voice commands. Hands-free calling and rear-view camera are standard. The Bose audio system provides well-balanced sound. The Bad: The additional performance looks good on paper, but doesn't translate into measurable improvements. The cabin can be quite loud at highway speeds. The Bottom Line: Infiniti's first foray into the waters of high-performance variants with the 2012 IPL G Coupe is more of a tentative toe than a full-blown cannonball. Photo gallery:2012 Infiniti IPL G CoupeThe 2012 IPL G Coupe represents many things to Infiniti. For starters, the Infiniti Performance Line (IPL) is the automaker's first dabble into the kind of performance premium sub-branding that makes German luxury cars bearing an "\/\/M" or "AMG" badge so alluring. If the automaker deems the IPL G a success, then perhaps we'll see the sub-brand expand. Could an IPL M Sedan be on the horizon? Let's first figure out if the IPL G Coupe in the CNET garage is worth the extra dough. Stepping up to the IPL G Coupe really only improves the G37 Sport in two measurable ways: it goes faster and it handles more sharply. The other changes, including a more raucous exhaust system and bright red leather sport seats, are more subjective improvements, but welcome additions nonetheless. It goes faster. We start our trip around the upgraded IPL G Coupe in the engine bay where, aside from the chrome IPL badge on the engine cover, not much is different from a standard G37. Yep, that's the same 3.7-liter VQ37VHR engine. However, what you don't see is that thanks to a few ECU tweaks, Infiniti's engineers have managed to squeeze an extra 18 horsepower out of this mill. Now the VQ37HDR outputs 348 horsepower and twists its crank to the tune of 276 pound-feet of torque. That torque number is only up by a scant 6 pound-feet, which may explain why the IPL G Coupe doesn't feel madly different from a G37 Sport. Zero to 60 takes about 5.0 seconds, just 0.2 seconds faster than the non-IPL model, which really makes any drag race between the two more of a driver's race than a hardware comparison. You'd really have to approach triple-digit speeds to feel any real difference between this and your neighbor's G37S. Infiniti managed to coax a few more ponies and pound-feet out of the G Coupe's 3.7-liter engine.You wouldn't need to do more than idle the engine to hear the difference. One of the most visible and audible upgrades the IPL G Coupe gets is a throaty exhaust system with larger dual tips. If you're like me and look back fondly on the fantastic rumble that the old G35 and 350Z had at idle and the exotic sounding howl of their 3.5-liter engines at full bore, you're in for a treat when you turn over the ignition push the start button in your new IPL G Coupe, because the growl is back. Firing off downshifts with the seven-speed automatic gearbox as I approached every traffic light triggered a rev-matching blip of the throttle and a satisfying bark from the new exhaust. And as I pulled away from each light, that same exhaust note was usually incentive enough to hold onto each gear for a few more revs and maybe open the throttle up just a bit more. Admit it, maybe 50-percent of the reason that most people buy a performance premium variant of any car is because they want to feel like a racecar driver. The IPL's exhaust goes a long way toward creating that illusion. I mentioned in passing that our IPL G Coupe was equipped with a seven-speed automatic transmission. This is a perfectly passable gearbox, but it's got nothing on the dual-clutch automated manual gearboxes present in BMW's performance offerings. If you're looking for the best performance from the IPL G, you'll want to save a few bucks and spec the six-speed manual gearbox. If you only signed up for the exhaust note, the rev-matching seven-speed auto will work just fine. The IPL G Coupe may not feel noticeably faster than the standard, but it sounds a heck of a lot better at full bore.Infiniti's gearbox features a manual shift mode, with some of the nicest paddle shifters in this segment, however the lag between a paddle input and engagement of the next gear restricted the manual shift mode's value to preselecting a lower gear for a freeway pass or forcing the transmission to hold a single gear through a twisty passage. For all other situations, just leave it in automatic Sport mode and let the rather capable computer do the shifting. It handles better. Tucked into the IPL G Coupe's wheel wells are large 19-inch aluminum alloy wheels shod in grippy 225-width tires up front and 245-width tires out back. Twenty-percent stiffer springs suspend the vehicle over these upsized rollers. Stiffer springs usually beget a stiffer ride, but thanks to tweaks that have been made to the IPL G Coupe's dampers, the sports coupe doesn't feel dramatically more bone-jarring over low-speed bumps and cracks than a standard G37 with the Sport package. You may recall that we Car Tech editors were of split minds as to whether the standard Sport package's ride is too harsh to begin with, but at least in this case the rougher ride matches the IPL's racy character. While the IPL doesn't feel much different from the standard G37 while moseying around town. I discovered on a windy road that its handling limits feel noticeably higher than more mundane Gs. Moreover, those limits are approached, met, and -- if you're not careful -- exceeded in a much more predictable and controlled manner than the standard G Coupe as well. Usually when a performance car features upgraded bodywork, it means that the automaker has slapped on a new front bumper, rear diffuser, side skirts, and sometimes a spoiler to make the car in question look more aggressive. This is exactly what Infiniti did with the IPL G Coupe -- spoiler and all. However, in this case the new body work actually serves an aerodynamic purpose, creating a zero-lift condition by helping to control how air moves around the vehicle at high speeds. If you look at the profile of a curvaceous sports car closely, you'll see that they're often shaped like airplane wings. Implications of flying cars aside, at high speeds air moving over the top of the car can end up moving faster than the air passing beneath it. In these conditions, you end up with what is called lift, a physical lightening of the vehicle due to air pressure. In an airplane, this is what you want. In a sports car, this can be fatal since the act of lifting a vehicle reduces the available friction that the tires can exert on the road. Infiniti claims that its aerodynamic additions cancel out lift, increasing the IPL G Coupe's vehicle stability and grip over a standard G37 Coupe. But otherwise, it's the same ol' G. Outside of the performance upgrades, the IPL G isn't very much different from the standard G. In fact, outside of the bright-red, 12-way power seats shod in brilliant red leather, you'd be hard-pressed to tell that you're not in the 2011 G37 Journey Sedan we tested last year. Fortunately, that isn't a bad thing. Bright-red leather seats shout "This is a special edition!" louder than the IPL badges.Cabin comfort options start with the standard 7-inch information display mounted at the top of the center stack. This gives drivers access to the climate control systems, audio controls for the standard USB\/iPod connection, XM Satellite Radio tuner, single-slot CD player, and Bluetooth hands-free phone system. This screen is also where the drive can display the view from the rearview camera, which is also standard. Normally optional in lesser G37s, the IPL comes standard with the rather loftily named Infiniti Studio on Wheels premium audio system by Bose. This 10-speaker rig performed, to my ear, about like any other Bose-branded audio system that we've tested. It would seem that Bose has tuned much of the boominess out of its car audio systems, as the G's setup produced a very balanced sound. However, strong bass is just two ticks of the bass level away and sound remains essentially distortion-free at most volumes as long as you don't get too far from center with the EQ's settings. The IPL G Coupe's cabin is a bit loud at highway speeds thanks to the firmer suspension and wheel package, which transmits more than a little road rumble into the cabin, and the louder exhaust, which sort of drones on while cruising. You'll definitely find yourself cranking the stereo to overcome all of the noise. Fortunately, the Bose system is up to the task. Unfortunately, your ears and stress level will be a bit tweaked by the time you're done with it an extended journey. Infiniti's top-tier infotainment system is standard at the IPL trim level.The 7-inch information display also serves as your window into a HDD-based navigation system which is fed data by the standard XM Satellite Radio receiver, downloading XM NavTraffic and XM NavWeather data and advisories silently in the background and using them to inform the system's routing and ETA estimates. The navigation system's 9.3GB hard drive also features space for audio storage. Maps show 3D buildings and landmarks and are attractive and easy to read. However, Infiniti's system does look a bit Fisher-Price when compared with the advanced graphics of BMW's and Audi's navigation systems. In addition to the touch-screen display, users can also interact with the IPL G's infotainment system via a physical controller that combines a knob and directional pad into one intuitive interaction point or via Infiniti's voice command system which allows users to access the different areas of the interface with spoken commands and dial contacts by name. In sum The Infiniti IPL G Coupe does what it sets out to do: improve over the performance of the standard G37 Coupe. Unfortunately, Infiniti's first foray into high-performance variants was more of hesitant testing of the waters with a toe than a full-blown cannonball. When you compare an M3 to a 335is, an C63 AMG to a C300, or even an IS-F to an IS350, you find that in most cases these performance variants look, feel, and perform like different cars from the models they're based on. This is not the case with the IPL G Coupe, which ends up feeling more like a model year update to last year's G37S than something special. The IPL G Coupe doesn't hold a candle to the M3s and C63 AMGs of the world, but at this price, it doesn't have to.The 2012 Infiniti IPL G Coupe starts at 49,800 when equipped with the six-speed manual transmission (or $5,600 more than a fully loaded G37 Sport). Our tester added $1,450 to that price for its seven-speed automatic transmission. For the extra buck, you bump the manual model's 17 city mpg and 25 highway mpg to more respectable 19 city and 27 highway mpg. All in and including a $895 destination fee, our Malbec Black IPL G Coupe rolls off of the lot at $52,345. That's almost $16,000 less than a similarly equipped BMW M3 Coupe... then again, the M car is probably a bit out of the IPL's league. For all of its premium performance pretenses, the IPL G Coupe actually stacks up closer in performance to a BMW 335is, a car that is still about $7,500 more. Placed on that scale, the Infiniti makes much more sense as pretty good value for the money.