With the simultaneous launch of the 5-series Gran Turismo and the Panamera, BMW and Porsche have created a new vehicle category. No, the segment doesn't require the vehicles be ugly, that's just a side effect. Instead, the new breed is characterized by sporty driving dynamics, luxury equipment, rear-seat opulence, and a slanted back that is as much about style as it is about functionality.

In addition to their physical and philosophical similarities, the BMW 550i GT and the Porsche Panamera S also have a lot in common on their spec sheets. Both cars boast V-8 engines, rear-wheel drive, 400 hp, four seats, and hefty price tags. Looking at these cars raises plenty of questions, so we got behind the wheel for a day of driving through cities, down highways, and over rural back roads in search of some understanding.

Mirror, mirror
Before we can move on though, we've got to address our insecurities, so we park the two hunchbacks side-by-side. The BMW, with its tall roofline and slightly raised ground clearance, looks a bit truckish when standing alone. But next to the Panamera, the 5-series GT looks natural and even somewhat pleasing. The truncated hatch hardly looks controversial. Instead, the GT seems merely to wear BMW's design du jour and if you're into the 5- or 7-series sedans, accepting the Gran Turismo is easy.

Unfortunately, the Panamera doesn't provide the same sense of resolution. The front end's broad, low hood and oval headlights establish the Porsche identity, but it's also rather bland. Boring, however, would be an improvement for the rear end. The awkward interplay of the fenders and hatch present an ungainly growth. Viewing the Panamera from a low front three-quarters angle allows you to hide the massive rear end behind the windshield and side glass, but that mass is lurking every time you look back at your parked Panamera.

Pricing prestige
These two hatchbacks show some differences when it comes to price, with a 550i Gran Turismo starting at $63,725 and a Panamera S beginning at $90,775 (both cars have cheaper, V-6 variants, as well). However, BMW narrowed the gap by providing us with a test car optioned up to $90,875, while our Porsche had a sticker of $106,210. Some of the main items helping to boost the BMW's price were night vision ($2600), a rear-seat entertainment system ($2200), head-up display ($1300), and a sport package with 20-inch wheels ($5200). There was less equipment added to the Panamera, although there were some extra-cost items that we might have expected to find on the standard equipment list, such as Bluetooth ($695), front and rear parking sensors ($600), ventilated front seats ($800), 19-inch wheels ($1950), and a heated steering wheel ($210).

On the road
Equipped with the $1320 Sport Chrono Package Plus, the Panamera offers three dynamic modes (normal, sport, and sport plus) to modify the engine, transmission, stability control, and suspension character. BMW's Driving Dynamics Control adds a fourth setting, comfort mode, and offers a broader bandwidth in varying the ride character. Despite that, with the BMW in its stiffest setting and the Porsche set to its normal mode, the Panamera is significantly more buttoned down. Body roll in the Gran Turismo is present in any quick turn, regardless of the setting, while the Panamera always remains flat and poised.

While both engines are rated at 400 hp, they're not quite equals. With two turbochargers mounted to its V-8, BMW's 4.4-liter musters 450 lb-ft of torque. Seamless, authoritative thrust is cushioned by the silky yet responsive eight-speed automatic transmission. With a wide plateau of torque available, shifting up early or neglecting to drop down that final gear isn't cause for concern.

Porsche's normally aspirated 4.8-liter makes 369 lb-ft of torque and pulls just as smoothly but issues a fierce bass growl in place of the BMW's subdued mechanical symphony. The raw vocals of the Porsche V-8 reiterate that this engine wants to be worked hard, with the revs kept as close to redline as possible. Hammering down the winding roads, we're glad to have the steering wheel shift buttons to manage Porsche's seven-speed, dual-clutch transmission. Even if they're a bit clumsy to learn, at least they allow you to keep your hands on the wheel. By contrast, manual shifting in the BMW is only available via the console-mounted shift lever.

While the Porsche lacks the BMW's grunt, its greater body control and more capable handling would likely make it faster around a track. Still, the BMW surprised us because it's no less engaging than the Porsche. Part of that, though is a weakness of the Panamera, which has a minor case of Nissan GT-R Syndrome. This is the phenomenon that afflicts incredible performance cars boasting uncanny 0-to-60-mph sprints, lateral grip, and lap times, yet failing to engage the driver the way we expect from a sports car. In the Panamera, the steering lacks the satisfying feedback cherished in Boxsters and 911s. The wheel still offers good feel, but the heavy weight masks some of the communication.

Returning to more relaxed settings and backing off the throttle, we rolled through rural downtowns and flowed with highway traffic to get a better feel for how these cars perform as luxury cruisers. Porsche's dual-clutch transmission is gentle when swapping gears, but a friction disc doesn't leave the line as gracefully as a torque-converter automatic. To compensate, the Panamera's transmission starts in second gear as long as the selector is left in automatic and you haven't activated sport plus mode. While its ride isn't harsh, the Panamera also transmits smaller impacts with more frequency and road noise than the BMW. For relaxed cruising, we'd pick the BMW hands down.

The back-seat battle
Both of these cars tout their rear seat appointments, aiming to offer the same comfort and luxury in the back as they do up front. Our 5-series GT was equipped with the $3650 luxury rear seating package, adding heated and ventilated rear seats, sunshades, and four-zone climate control. Inviting ivory leather and a panoramic sunroof create a spacious and airy cabin. By raising the rear seat cushions in relation to the front seats, BMW provides an excellent view out the windshield. The comfortable chairs, luxurious materials, and superior visibility make the Gran Turismo worthy of a chauffeur. The Panamera takes the opposite approach, tucking back-seat passengers into a dim, sequestered cave. The rear seats sit lower than the tall front chairs, allowing just a sliver of visibility out the windshield and requiring passengers to lower themselves into the car.

Comfort and space in the two cars are roughly equal but the ambiances are starkly different. The Gran Turismo is suited to carrying a pair of couples out to dinner or to a weekend destination, with conversation freely flowing. In the Panamera, the isolation of the rear seats imbues a sense of second-class citizenship despite the beautiful finishes. Instead of a true sedan, we think of the Panamera's back buckets as merely an opportunity to wow two additional friends with the Porsche's capability. The slight shortcomings in practicality also make us wonder if more than a few Panamera shoppers might just end up with Porsche's Cayenne SUV instead. Still, some of our editors preferred the Panamera's coddling sport bucket seats to the traditional bench-like feel in the Gran Turismo.

Up front, the cockpits are also distinctly different. The driver's position in the 5-series puts you high and upright, not unlike an SUV. The Panamera's steeply raked windshield is further from the driver creating a sleek, sports-car feel. Unfortunately, the Panamera's tiny rear window is made even smaller with an active spoiler that lifts at high speeds, compromising rearward visibility.

Buttons - or lack thereof - also define the cabins. BMW packages many of its controls in the ten-inch screen and rotary controller of its iDrive system, while Porsche has carpeted the entire console and center stack with buttons for climate, audio, navigation, and vehicle dynamics functions. Porsche's approach may be the more straightforward presentation, but we've become pretty familiar with iDrive and can easily navigate through the menus now. The sheer number of buttons in the Panamera means it will be some time before we feel comfortable making adjustments on the fly.

Defining the class
Despite their similarities, these two cars have unique personalities. BMW's Gran Turismo is a bastion of luxury and comfort. The Porsche is a sports car first and a luxury car second. That the Panamera is a credible four-door sports car may be a reason to buy for some, but the Panamera isn't the sedan that we expected. Against another competitor - say the Maserati Quattroporte - the Porsche may truly shine. But in this new segment, we expect luxury-sedan accommodations along with the sporting credentials.

The Gran Turismo perfectly fulfills that mission to carry four people - in fact, for passengers, the rear seat is better than the right front. The BMW also offers better driving comfort combined with the ability to make a dramatic transition to a capable sport mode. And with a smidge of self-restraint, any buyer can get a well-equipped Gran Turismo at a five-figure discount compared to a Panamera. For delivering sport, luxury, and comfort for four at a reasonable price, the 5-series Gran Turismo sets the standard in this new class.

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