There's no mistaking it for anything but a Porsche, but with four doors and four full seats, the Panamera is like no previous Porsche.

Styled by a team of in-house designers under the direction of Michael Mauer, the Panamera is 195.7 inches long, 76.0 inches wide and 55.8 inches tall — making it slightly shorter but wider and lower than the Maserati Quattroporte, with which it shares a coupelike profile.

As with all such silhouettes, "the real challenge is giving the rear-seat passengers enough headroom," says Mauer. "The way that was done was to give a visual message that it's a coupe — look at the chrome around the window — but make the roofline higher."

Unlike the Pininfarina-designed Maserati, however, the new Porsche has a large liftback, for easy access to the trunk. And the rear seats are individual, with tall backrests that can be electronically reclined. Nominal trunk capacity is put at 15.7 cubic feet, but folding the rear seats increases capacity to 44.7 cubic feet.

Giving the Panamera ample luggage space was key, says Mauer, as was making the car a genuine four-seater and not just another 2+2. Even the tallest folks will find plenty of headroom, legroom, shoulder room and hip room in back. But all will be grateful for the omission of a center seat. "It's a true four-seater, not a five-seater with a compromised middle seat," says Mauer. "By putting only two seats in back, we were able to move the rear seats closer together and get the body to taper back."

According to Mauer, tapering the body is what keeps the Panamera looking like a Porsche, along with other design decisions all over the body.

The Panamera will be available with the choice of two 4.8-liter V8 direct-injection engines, both now in use in the Cayenne. The S and the 4S models get a naturally aspirated engine rated at 394 hp at 6,500 rpm and 369 lb-ft of torque at 3,500 rpm. In turbocharged form, the four-valve-per-cylinder engine delivers 493 hp at 6,000 rpm and 516 lb-ft of torque at just 2,250 rpm.

Gearboxes are a standard six-speed manual on the S and, for the four-wheel-drive 4S and Turbo, Porsche's newly introduced seven-speed dual-clutch PDK unit. Both are mated to an automatic stop/start system, a first for Porsche, which reduces fuel consumption by shutting off the engine when the car comes to a stop.

Porsche claims the Panamera is good for 0-to-62-mph times of 5.6 seconds, 5.0 seconds and 4.2 seconds, respectively, for the S, the 4S and the Turbo. The Turbo also is capable of hitting 100 mph in 9.0 seconds and reaching a top speed of 188 mph.

North American sales will start in October, with prices of $89,800 for the base rear-wheel-drive Panamera S and $93,800 for the four-wheel-drive Panamera 4S. Topping the lineup will be the extensively equipped four-wheel-drive Panamera Turbo, with a $132,600 price on par with the Quattroporte GTS and the upcoming Aston Martin Rapide.