A year ago, when Porsche rolled out its first homegrown V-6 for a production car, the Panamera, the introduction came with an odd disclaimer that was hard to swallow.

The direct-injection gasoline 3.6L V-6 makes 300 hp, which might have been impressive 10 years ago. But today, no fewer than 14 V-6s on the road produce at least that much power in less-expensive vehicles.

So a straight-faced Porsche engineer told Ward’s last summer the Stuttgart auto maker synonymous with high-performance race cars doesn’t want to “be in a horsepower war,” because horses are hungry and need to be fed, which is another way of denouncing gas-guzzlers.

How many people want to spend six figures on a car from a company whose engineers are “holding back on power?”

Such proclamations sound ridiculous – until the car-shaped key is inserted in the ignition to fire up this naturally aspirated powerplant in the ’11 Panamera 4, the strong-selling 4-passenger gran turismo.

Engage the 7-speed dual-clutch automatic transmission, start rifling through the gears and just listen to the high-rpm wail as the shoulders stretch the seat leather ever so slightly.

Suddenly, all that hand-wringing about a paucity of “horsepower” vanishes like a magician’s coin, because the engine sounds and feels like a lot more than 300 hp. It growls and howls at a lower octave than other V-6s, which gives it a rich, beautiful sonorous exhaust tone when pushed.

If this is Porsche surrendering to a horsepower war, what should we expect when the troops are mobilized? It’s easy to gush about a car that oozes sensuality and sounds spectacular, but a dose of reality is in order. The base price of the Panamera 4 is $78,900, and the fully loaded model evaluated by Ward’s editors is a hair under $100,000.

True, four V-6 Ford Mustangs can be had for less than that, and every one of them will deliver 5 hp more, as well as a thrilling pony-car experience.

The Panamera has five doors, a comfortable back seat and weighs 542 lbs. (246 kg) more and yet, oddly enough, feels fully capable of running with any V-6 Mustang.

That’s because in the case of the Panamera, Porsche demonstrates that an engine is only as good as the transmission it’s hooked to, the soundness of the chassis and suspension and the electronics that govern the entire driveline. Holistic vehicle development is grossly under-rated.

Customers have discovered the merit of this engine, which powers 40% of the Panameras sold in the U.S. since the beginning of 2010. The Panamera remains Porsche’s best-selling car, with 4,141 U.S. deliveries through July, according to Ward’s data.

The new water-cooled 90-degree all-aluminum V-6 comes from good stock: the 400-hp 4.8L V-8 that powers the Panamera S, Panamera Turbo and Cayenne cross/utility vehicle. It’s a beast of a V-8 (especially when turbocharged), and lopping off two cylinders saves development time and cost.

Porsche builds the new V-6 at its engine plant in Zuffenhausen, Germany.

The V-6 and naturally aspirated V-8 share many specs, including compression ratio (12.5:1), specific output (83 hp/L), bore and stroke (96 x 83 mm), direct injection, dual overhead camshafts, integrated dry-sump lubrication, infinitely variable intake camshaft adjustment and VarioCam Plus variable valve lift.

Even the gear ratios are identical for the 7-speed double-clutch Porsche Doppelkupplungsgetriebe (PDK) gearbox, which ensures lightning-fast shifts in nearly every possible drive mode of the V-6 Panamera.

The longitudinal installation under the hood is the same, as well, deep in the engine bay for a low center of gravity and closer to the firewall to make the vehicle less nose-heavy.

For enhanced refinement, a balance shaft rotating in the oil sump offsets the free-mass momentum that can create noise, vibration and harshness issues.

Standard on every Panamera is Porsche’s Auto Start Stop function that sometimes shuts off the engine at stop lights. Release the brake pedal and the engine springs back to life, even before the accelerator has been depressed.

It’s not the smoothest stop/start system we’ve experienced.

Enthusiasts might not like it, but Porsche needs this technology if it wants to continue selling vehicles that meet U.S. fuel-economy standards of 35.5 mpg (6.6 L/100 km) by 2016. By 2025, that fleet average is headed toward 54.5 mpg (4.3 L/100 km).

In the Panamera, stop/start is of questionable value, because it can be switched off whenever the driver likes, via a button on the center console.

In vehicles equipped with the optional high-performance Sport Chrono Package Plus, stop/start won’t work when the vehicle is in Sport Plus mode.

With this top-end package, the Panamera can be driven in three modes: normal, Sport and Sport Plus. All three are good.

The chosen mode dictates how the engine controller and transmission will respond to throttle inputs and driving style: The more aggressive the throttle input, the higher the gearshift occurs in the rpm range.

The easiest way to illustrate the shift logic is to drive the Panamera steadily at about 40 mph (64 km/h). In normal mode, the PDK likely will be in sixth gear and engine speed will be about 1,500 rpm.

Press the Sport button, and the transmission kicks down to fifth gear and engine speed rises to about 2,000 rpm. Hit the Sport Plus button, and fourth gear arrives at an engine speed just under 3,000 rpm.

The car is happy in whatever mode is selected, letting the driver decide how fuel-efficient he wants to be.

’11 Porsche Panamera 4
Vehicle type Front-engine, all-wheel-drive, 4-passenger gran turismo
Engine 3.6L DOHC DI all-aluminum V-6
Power (SAE net) 300 hp @ 6,200 rpm
Torque 295 lb.-ft. (400 Nm) @ 3,750 rpm
Bore x stroke (mm) 96 x 83
Compression ratio 12.5:1
Transmission 7-speed double-clutch
Wheelbase 115 ins. (292 cm)
Curb weight 3,880 lbs. (1,760 kg)
Base price $78,900
Fuel economy 18/26 (13-9 L/100 km)
Competition Audi A8, BMW 7-Series, Lexus LS, Mercedes S-Class
Pros Cons
Best 300 hp ever Stutter-step at launch
Moves tach needle like battleaxe Requires premium fuel
Stop/start capable System doesn’t work much

Leaving a stoplight in most casual driving situations, in normal mode, shifts will come quickly and the engine sounds like it’s barely laboring. In these circumstances, it makes no sense to be in either Sport or Sport Plus, because the engine will have to work harder than necessary.

In Sport Plus, shifts always come north of about 4,000 rpm, even if you’re behind a gravel hauler pulling away from a stoplight. The slower your ability to accelerate through the gears, the more Sport Plus will conjure up images of a root canal.

Also, the transmission starts out in second gear in both normal and Sport modes under light throttle, to save fuel.

The only way to launch in first gear when accelerating moderately is in Sport Plus.

But with an open road ahead or at a test track, launching in wide-open throttle is nothing short of awe-inspiring. In all three modes, the transmission drops to first gear and the tachometer swings like a battleaxe just shy of the 6,700-rpm redline.

Hold on tight, keep it at wide-open throttle, and, in what feels like the blink of an eye, second gear surpasses 6,000 rpm, then third gear, too. Once you back off on the gas, the shifts come at lower engine speeds. The PDK in the Panamera is like a continuously variable transmission, only smarter, faster, smoother and an absolute blast to drive.

Sure, there are paddles for shifting the PDK, but don’t bother. There’s much to learn from a transmission that’s smarter than you are.

A sprint to 60 mph (96 km/h) comes in 5.6 seconds for the all-wheel-drive Panamera 4 and 5.8 seconds for rear-drive models with the Sports Chrono Package Plus. The car is a little slower without it.

The only complaint about the new V-6 may not be the fault of the engine but the programming of the transmission. From a standstill, in all three drive modes, whether launching from first or second gear, there are slight stutter steps that feel like gearshifts even before one has occurred.

We’ve noted this before, and Porsche has said the PDK is designed to mimic the slight lag experienced with the previous Tiptronic torque-converter transmission, for maximum efficiency.

The hesitation is subtle, then gone, once the transmission shifts into third gear.

If this is the price of efficiency Porsche owners must pay going forward, few will quibble.

After driving 407 miles (655 km) at varied highway speeds, all of it in default mode, we returned 21.4 mpg (10.9 L/100 km), according to the trip computer.

We then began playing with Sport and Sport Plus modes for the next 50 miles (80 km), none of it on the highway, and managed 20.8 mpg (11.2 L/100 km).

Those are decent mileage figures for a car intended to do much more than take the kids to their violin lessons.

If stop/start is a piece of the technology quiltwork that enables numbers such as these and permits Porsche to continue selling vehicles in the U.S., then so be it.

The world would rather see the auto maker taking bold steps like this than hoist the white flag of surrender.

Porsche should take Cheap Trick’s unforgettable advice:

Surrender, surrender, but don’t give yourself away.

tmurphy@wardsauto.com