Used 2012 Porsche Panamera

So get this: The journalists attending the launch of the 2012 Porsche Panamera S Hybrid were invited to take part in an economy challenge. Whoever got the best mileage would get a prize.

We ignored the request. To present a 375-horsepower, 4,365-pound Panamera as an eco warrior is palpably absurd. This might be the "most economical Porsche" ever, but it's no Prius.

Its task is to combine V8 performance with V6 efficiency, making the Panamera customer feel more worthy without diluting their "Porsche" experience.

The Tech Bits
Porsche's absorption into the Volkswagen empire might have upset the purists, but it has given the company access to a vast swath of technology that it could have had no hope of developing alone. Accordingly, this car's hybrid powertrain is shared with the Cayenne S Hybrid and VW Touareg Hybrid and uses a supercharged, direct-injection gasoline engine pinched from the Audi S4.

The latter measures 2,995cc and offers up 333 horsepower. Add the electric motor and you have a combined output of 375 hp at 5,500 rpm and 427 pound-feet of torque, available at just 1,000 rpm. By contrast, the 4.8-liter V8 in the old-school Cayenne S knocks out 400 hp and 369 lb-ft of torque.

This is a parallel hybrid that sandwiches the electric motor between the engine and the eight-speed automatic transmission. It also has a clutch between the engine and motor so that they can drive the gearbox independently. At speeds up to 103 mph, the system analyzes the angle of the throttle pedal and is able to decouple the engine completely when the car is coasting, boosting its cruising efficiency. Electrical energy is stored in a nickel-metal hydride battery pack, mounted in the rear to help achieve a 51/49 mass split.

The Hybrid is only available with rear-wheel drive. Porsche's engineers were forced to lower the engine to incorporate the hybrid system, and this left no room for an additional propshaft.

The Experience
With a fully charged battery, Porsche claims the Panamera can be driven up to 1.24 miles on electricity alone. An E-Power button on the fascia helps optimize its electric potential by remapping the throttle to discourage the activation of the gasoline engine. It works, to a point. In slow-moving traffic, the near-silent progress is genuinely appealing, but traffic jams are really the extent of its talents. As soon as the road opens, you'll be calling for internal combustion.

No less intriguing is the impact of the electric motor on the power delivery. The instantaneous slug of torque is enough to light up the rear tires and send the traction control into hyperdrive. This makes the Hybrid feel faster than the raw figures suggest. Porsche claims zero to 60 mph in 5.7 seconds and a top speed of 167 mph, compared with 5.2 seconds/175 mph for the V8 and 6.0/160 for the V6 Panamera.

Achieving such figures relies on using what Porsche calls the Boost mode, in which the engine and motor deliver power simultaneously to the gearbox. This relies on the battery being suitably charged, so the feature cannot be used indefinitely. Calling for maximum thrust also highlights the comparative lack of refinement. The Panamera might have a quartet of extravagant tailpipes, but the Hybrid lacks the acoustic charm of both the V8 and Porsche's own V6. It sounds strained under full load, denying the Hybrid the sonorous soundtrack that has always been a core component of the Porsche DNA.

Gone, too, is the rapier-like throttle response. Prod the throttle and there's a pregnant pause while the computers decide which of the systems to deploy. The near-telepathic relationship between right foot and response that you find in a 911 or even a standard Panamera is lacking here. The Tiptronic transmission is also less engaging than the double-clutch systems found in other Panameras, and the gearing is exceptionally long. Top speed is reached in 6th, with an overdrive 7th and 8th to promote fuel efficiency.

All of our test cars were fitted with Michelin Pilot Sport all-season tires, measuring 225/45 at the front and 285/40 at the rear, with a diameter of 19 inches. They are speed-limited to 149 mph but offer less rolling resistance than more conventional rubber. Without a more traditionally shod car for comparison, it was hard to determine how much grip they give away, but there's no question that they're significantly noisier and less aesthetically pleasing.

When we tested the Cayenne S Hybrid we reported an awkward, jolting transition between regenerative and friction braking. In the Panamera, though, this problem seems to have been largely overcome.

The Economics
On the New European Driving Cycle (NEDC) the Hybrid achieves 34.6 mpg with low-rolling-resistance tires or 33.2 mpg on familiar boots. This compares well with both the V8 (22.4) and the V6 (25.3). If you're an urbanite, there's no denying the Hybrid offers significant fuel savings, even though it's hard to imagine too many Panamera customers being concerned about the cost of gasoline.

Outside the city, though, the case for the Hybrid is less convincing. Here the V6 becomes the primary tool of propulsion and if you want to progress, it will need to be worked hard. The hybrid kit carries a significant weight penalty — this Panamera tips the scales at 4,365 pounds versus 3,968 for the V8. In the real world, that impacts both performance and economy. On a twisty section of our European test route, we saw consumption drop to the mid-teens. Don't expect to get close to the official average if you drive it as Ferry Porsche intended.

The Rest
Anyone keen to proclaim their green credentials can point to the hybrid badges on the rump and front doors. The rest of the car, though, mimics the normal Panamera S, which may or may not be a good thing. Two years on from its launch, its stretched 911 proportions continue to polarize opinion. Inside, there's a new E-Power meter alongside the familiar instruments, and the onboard computer now dishes up some pretty graphics explaining what's propelling what. The rest of the cabin is familiar, though, and the over-the-shoulder visibility remains as lousy as ever.

To help justify a $5,200 premium over the V8, the Hybrid features air suspension and adaptive dampers as standard, both of which cost extra on the standard "S." There's variable-assist power steering too and...hold the front page...a rear wiper.

By carefully managing the distribution of the hybrid components, Porsche has preserved the balance and precision of the Panamera chassis. No car this big and this heavy has any right to handle this well. The steering and poise are superb and on twisty roads, the Panamera shrinks around the driver like few other cars. The chassis is as entertaining as its looks are challenging.

Final Thoughts
In Europe, the Panamera S Hybrid makes little sense. The forthcoming Panamera diesel will be more economical (37.4 mpg), almost as fast (zero to 60 mph in around 6.5 seconds), more refined and $39K cheaper according to U.K. prices.

In the U.S., the position is different. The diesel may eventually appear, but for now the Hybrid is the only choice if you want to pose as a bunny-loving, tree-hugging Porsche owner. Even Stuttgart insiders admit that the Hybrid will be bought as much for its badge as it is for its engineering, but reckon there are plenty of people anxious to make such a statement. They expect around 10 percent of customers to tick the Hybrid box.

Those who do will receive a giant performance car working to a curious agenda. Here is a Porsche that sacrifices its dynamic competence and aural pleasures in favor of fuel-efficiency gains that will only really be felt by urban dwellers. The result is a car that forever feels at war with itself.

Edmunds attended a manufacturer-sponsored press event to facilitate this report, which originally appeared on insideline.com.