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Looking over the shoulders of Hans Werner Aufrecht and Erhard Melcher, the founders of German tuning group AMG, as they built up their first Mercedes-Benz 300 SE in the 1960s would have been a banner moment for any automotive performance enthusiast. I felt I was onto a similar opportunity when Volvo flew me down to Southern California to meet members of Polestar, an independent company devoted to giving Volvo models a performance upgrade.

Volvos may have a reputation as being the safest cars in the world, but under the hands of Polestar, they can become quite fast. The company began working with Volvo models in 1996, developing them for touring car races in Europe. Over the last few years, it has become the official tuner partner for Volvo, designing upgraded versions of standard models for full production. While this partnership bears some resemblance to AMG and Mercedes-Benz, Polestar remains an independent company.

At the Autoclub Speedway in Fontana, Calif., I asked Thed Bjork, one of the Polestar racing drivers, what he felt was the company's most significant moment. He pointed out the team's 2009 win of the Swedish Touring Car Championship in a Volvo C30 with extensive Polestar modifications. Designed to meet FIA S2000 regulations, it was Polestar's first full race car project.

Volvo would later release a limited-edition C30 Polestar , the main modification being performance-oriented engine control software developed by Polestar.

Now, I was in Southern California to drive the latest Polestar editions. We had the 2015 Volvo V60 Polestar, a wagon, and the 2015 Volvo S60 Polestar -- this model almost identical to the former but with a sedan body. Differing from the 2015 Volvo S60 that CNET editor Antuan Goodwin reviewed earlier this year, the Polestar edition enjoys an extensive list of performance upgrades.

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Polestar begins with the standard 3-liter six-cylinder engine, but swaps out the turbocharger for a twin scroll version and adds an intercooler. That and updated control software bring the output up to 345 horsepower and 369 pound-feet of torque. Polestar swaps in a 2.5-inch stainless-steel exhaust system with 3.5-inch tips.

I began the day driving the V60 Polestar on a public road route, and noted how quickly I had topped 70 mph on the freeway. The car rode so smoothly that I had barely noticed the speed build up. Paying more attention to the LCD speedometer, I followed the route toward the nearby mountains. As the roads became rougher, I was impressed at the buttery ride quality of the V60.

I had been told that Polestar added an active exhaust system, so I floored it with the transmission in its standard Drive mode. The exhaust sound was gentle but the propulsion was strong. Slapping the shifter over to Sport, I floored it again and was rewarded with a deeper, more aggressive note from the twin exhaust pipes.

When I found curvier roads I let the six-speed automatic shift in Sport mode as I modulated the brakes and accelerator. To engage aggressive shifting on the part of the transmission, I had to floor it on a straight, brake hard for a turn, then floor it again. This transmission was looking for some aggressive behavior. Tapping the steering-wheel-mounted paddles to bring in manual shifting, the automatic was able to shoot off my requested gear changes with authoritative quickness.

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Although this transmission was the same as found in the standard V60 and S60, Polestar got in and updated the software, allowing for those quicker shifts. Likewise, the company reengineered the software for the Haldex all-wheel-drive system. Turn off the electronic stability control (which, Bjork assured me, is never completely turned off), and the car biases more torque to the rear wheels.

Further up in the mountains, I got behind the wheel of the S60 Polestar. The ride here felt a little more visceral, a little more mechanical. Later, Polestar's press manager, Johan Meissner, explained that the V60 Polestar's extra 66 pounds required more stiffening in the rear suspension, and its wagon body gave it more rigidity. Ultimately, I preferred the ride quality of the wagon, along with its greater utility and potential sleeper status.

The S60 Polestar had the same sensitive throttle response as the V60 Polestar, making it easy to modulate. At the same time, the brakes had all the grab I could want. Unlike typical production car brakes, which don't bring much stopping power to bear in the first quarter of pedal travel, these were ready to grip from the first tip-in. In other words, these were true performance brakes.

At the front wheels were six-piston Brembo calipers bearing the Polestar logo. Gary Cogis, Polestar's US press manager, explained to me that the company worked with Brembo and Volvo extensively on these brakes. At first, Polestar tried slotted discs, which reduce weight and cool faster, but Volvo engineers noticed too much noise under heavy braking, so they specified solid discs. This move was made to ensure that the V60 Polestar and S60 Polestars would be as comfortable on the road as other Volvo models.

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While the suspension architecture is basically the same, Polestar upgraded bushings and stabilizer bars, and added an aluminum and carbon fiber strut brace. This latter piece looks like a cable rather than the typical bulky aftermarket strut braces available. Most importantly, Polestar opted for Ohlins dual-valve dampers, which, Cogis pointed out, see their only other production car use on the Lamborghini Aventador.

On the S60 Polestar and V60 Polestar, these dampers are manually adjustable. Delivered at medium adjustment to mix performance and comfort, owners can turn a bolt at each wheel to opt for a harder or softer ride. Here, Polestar could have implemented an automated system where the driver could push a button to dial in different ride characteristics. However, this level of engineering was beyond the scope of the project.

Piloting the S60 Polestar along a set of mountain curves, it proved a very pliable ride, able to handle tight turns at speed. A few times I had the tires squealing, but the car remained composed and easy to handle. As with the standard S60, I could adjust the electric power steering between three settings: soft, medium and hard. I preferred the more solid feeling of the hard setting, which didn't interfere with the ease of turning the wheel in low-speed conditions.

After this scenic and often sedate mountain cruise, the real fun began. Volvo set me up for a track drive with the S60 Polestar. This road course included two good straights, four chicanes, and a couple of tricky corners. The car was the same one I had just been driving, although Polestar personnel let some air out of the tires for a bigger contact patch.

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Turning off stability control, I rolled out onto the track and floored it for the first straight. Opting for the Sport shifting program, I focused on braking and acceleration, looking for the optimal turn-in points. The pedal response was all I could want, each turning into a precision instrument letting me get just the right amount of braking or power modulation.

In the turns, the dampers stretched a bit more than I would have liked, but I was able to feel the car rotate under me on the tighter turns. There was a bit of sway to one side as I set up for the first turn of a chicane, swapping to the other side as I reset the wheel for the next apex. To be honest, I wanted more power when I accelerated out onto the straights. The Sport program for the transmission was up to aggressive shifting, but the car betrays a softer character, showing that the track is not its first home.

Using manual shift mode for additional laps, I found myself frequently overrunning second, making the car jump to third. I admit my own lack of expertise here, but the car ran so quietly that I couldn't easily tell when it was hitting redline without monitoring the tach. Getting the hang of it a bit more, I still found myself yearning for more power. Likewise, I would have liked to try this car with the suspension screwed down a little tighter.

Talking with Polestar's Messner later on, he mentioned that the Polestar editions of the S60 and V60 were not intended to be racecars for the road, but road cars with a performance edge. I wouldn't be pitting the S60 Polestar against a BMW M3 on a track day, but it seemed like it would measure well against an Audi S4 or S5. More to the point, the V60 Polestar, as a wagon, occupies rare ground in the automotive world. It is the only hot wagon available in the US.

That is to say, it was the only hot wagon available. For the 2015 model year, Volvo only offered 750 Polestar editions in total. The US received a large amount, 80 V60 Polestars and 40 S60 Polestars. Fully loaded with all available features and at about $60,000 each, those models sold out in five days. Volvo's US vice president of communications, Dean Shaw, told me that Volvo is seriously looking at offering another run for the 2016 model year, but no decisions have been made as yet.