Audi let us compare a stock A5 3.2 FSI, equipped with the 265-hp V-6, against the lightweight concept with the 2.0-liter engine dialed back from 258 pound-feet of torque to deliver the same 243 as the V-6. We can attest to the fact that a 500-plus-pound reduction makes for a stunning dynamic improvement. Turn-in becomes more agile, the car can be tossed around with ease, and the 211-hp engine feels far stronger than its numbers suggest.

A regular A5 3.2 FSI seems downright clumsy in comparison. Audi claims the lightweight concept is 0.3 second quicker to 60 mph than the V-6. In our testing, the A5 V-6 ran from zero to 60 mph in 5.8 seconds, so we expect the lightweight concept to hit 60 mph in 5.5 seconds, a 0.7-second improvement over a standard A5 2.0T.

Audi originally intended the concept to emulate the performance of the V-8–powered, 354-hp S5, but, despite the weight loss, the concept still can’t match the S5’s acceleration. We understand that a second concept is currently being built—and we wouldn’t be surprised if this one was equipped with the 265-hp, 2.0-liter turbo four from the TTS. With that much power, the four-cylinder lightweight just might be able to trounce the S5’s V-8.

Most “efficiency” concepts make us dread the future; this one gives us hope.

Liftoff!

The RS 6 Avant is a car that suits any enthusiast’s taste. For example, if straight-line speed appeals to you, look no further. There are a number of high-performance sedans and station wagons on the market now—the BMW M5, the Cadillac CTS-V, the Jaguar XFR, and the Mercedes-Benz E63 AMG, for example—that make 500 or more hp. But at a lofty 580 hp, the Audi RS 6 tops them all. Zero to 62 mph takes a claimed 4.6 seconds, and top speed is governed at 155 mph as standard, with the option to have it raised to 174 mph—hence, our indicated 180. (Audi speedometers are a touch optimistic.)

If you’re more interested in handling, the RS 6 won’t disappoint you, either. The all-wheel-drive system and the 19-inch wheels with 255-series tires—20s with 275-series rubber are optional—raise the limits of adhesion considerably versus those of a regular A6 Avant. Push this car hard, and you note that it carries a lot of weight up front, but you can steer it with the throttle until the stability-control system kicks in, although that happens earlier than we’d like, even in the sportiest setting. It takes guts to turn it off completely, but it’s worth it.

The 5.0-liter V-10 in the RS 6 is closely related to the naturally aspirated V-10 available in the Audi S6 and outgoing S8, as well the R8 5.2 and the Lamborghini Gallardo. Direct-injected and twin-turbocharged, the RS 6’s is the most powerful iteration of this awesome powerplant. The RS 6 Avant comes only with a six-speed automatic, which shifts smoothly and rapidly and is well integrated with the engine. We wouldn’t mind a manual transmission, but it would probably be hard to find a unit that could handle 480 lb-ft of torque—available from 1500 rpm—and fit the RS 6’s platform.

A Whole Lotta Capability

Optional carbon-ceramic brakes are available with the larger wheels and tires. Those stoppers weigh about 27 fewer pounds than the standard cast-iron brakes and are super-easy to modulate. Audi promises that under normal driving conditions they will last close to 200,000 miles. However, we wish they were quicker to respond in wet weather, and there is perhaps not enough difference in performance from the standard brakes to justify the $11,000-plus extra cost. We like that the R8 supercar’s optional carbon-ceramic brakes are aggressive, and we wish the RS 6’s system had more of the same attitude.

The chassis makes extensive use of aluminum components, and a three-step electronic suspension is available. The softest setting is perhaps the most harmonious. It is by no means detached, and it gives ample feedback to the driver without being punishing. After normal mode, the sport setting stiffens up the car further, but it only makes sense if you actually take this family hauler to the track. Off-road capability is limited by the wheels and tires—and ground clearance—but we can attest that the Quattro all-wheel-drive system will let you drive circles around the RS 6’s rear-drive competitors in the snow. Unfortunately, the big engine, all-wheel drive, and everything else add up to a curb weight near 4500 pounds. But at least the RS 6’s capabilities mask the bulk fairly well.

Being a modern Audi, the cabin is extremely well executed, with amazing sport seats and the company’s trademark attention to detail. The base A6 will be replaced within two years, so this interior is a bit dated in terms of product cycle, but even then, the RS 6’s cabin cedes little to its competitors. And the RS 6 Avant is a great family car, spacious and confidence-inspiring, as are the more pedestrian A6 models.

Expensive, Thirsty, and Heavy

Is there anything not to like? Well, the RS 6 Avant is very pricey, at an equivalent of nearly $160,000 in Germany, and the 11-mpg average it returns when you push this beast hard is not good. Officially, it gets 17 combined mpg in the European cycle, and that’s a figure you can better, but the car just invites shenanigans—any good intentions waft out the massive exhaust pipes as quickly as you can downshift from sixth gear to second for a surprise pass on a back road.

There’s also the fact that the RS 6 Avant also feels a little too well behaved and detached. Blame the weight. The car is more than willing to play if you’re up for it, but you feel as if it has to work to go exactly where you want it. The previous RS 6, with its 450-hp twin-turbocharged V-8, felt more agile and, subjectively, just as fast as the current model, and it sounded more immediate than the current car.

One of the Greats

But charging through the twisties and gobbling up miles on the motorways, we think no other car in this league offers such an intoxicating combination of attributes. Behind the wheel, 120 mph is always just a few seconds away, and the speed can be scrubbed off right now if you need to make a good impression on a radar gun. Although V-10 engines may not be the thing in Formula 1 anymore, listening to the RS 6 at full throttle is one of the greater experiences in motoring. We just wish we could get it in the U.S.—and didn’t have to worry about those pesky speed limits everywhere else.

(BY JENS MEINERS, PHOTOGRAPHY BY MATTHIAS KNÖDLER)

Liftoff!

The RS 6 Avant is a car that suits any enthusiast’s taste. For example, if straight-line speed appeals to you, look no further. There are a number of high-performance sedans and station wagons on the market now—the BMW M5, the Cadillac CTS-V, the Jaguar XFR, and the Mercedes-Benz E63 AMG, for example—that make 500 or more hp. But at a lofty 580 hp, the Audi RS 6 tops them all. Zero to 62 mph takes a claimed 4.6 seconds, and top speed is governed at 155 mph as standard, with the option to have it raised to 174 mph—hence, our indicated 180. (Audi speedometers are a touch optimistic.)

If you’re more interested in handling, the RS 6 won’t disappoint you, either. The all-wheel-drive system and the 19-inch wheels with 255-series tires—20s with 275-series rubber are optional—raise the limits of adhesion considerably versus those of a regular A6 Avant. Push this car hard, and you note that it carries a lot of weight up front, but you can steer it with the throttle until the stability-control system kicks in, although that happens earlier than we’d like, even in the sportiest setting. It takes guts to turn it off completely, but it’s worth it.

The 5.0-liter V-10 in the RS 6 is closely related to the naturally aspirated V-10 available in the Audi S6 and outgoing S8, as well the R8 5.2 and the Lamborghini Gallardo. Direct-injected and twin-turbocharged, the RS 6’s is the most powerful iteration of this awesome powerplant. The RS 6 Avant comes only with a six-speed automatic, which shifts smoothly and rapidly and is well integrated with the engine. We wouldn’t mind a manual transmission, but it would probably be hard to find a unit that could handle 480 lb-ft of torque—available from 1500 rpm—and fit the RS 6’s platform.

A Whole Lotta Capability

Optional carbon-ceramic brakes are available with the larger wheels and tires. Those stoppers weigh about 27 fewer pounds than the standard cast-iron brakes and are super-easy to modulate. Audi promises that under normal driving conditions they will last close to 200,000 miles. However, we wish they were quicker to respond in wet weather, and there is perhaps not enough difference in performance from the standard brakes to justify the $11,000-plus extra cost. We like that the R8 supercar’s optional carbon-ceramic brakes are aggressive, and we wish the RS 6’s system had more of the same attitude.

The chassis makes extensive use of aluminum components, and a three-step electronic suspension is available. The softest setting is perhaps the most harmonious. It is by no means detached, and it gives ample feedback to the driver without being punishing. After normal mode, the sport setting stiffens up the car further, but it only makes sense if you actually take this family hauler to the track. Off-road capability is limited by the wheels and tires—and ground clearance—but we can attest that the Quattro all-wheel-drive system will let you drive circles around the RS 6’s rear-drive competitors in the snow. Unfortunately, the big engine, all-wheel drive, and everything else add up to a curb weight near 4500 pounds. But at least the RS 6’s capabilities mask the bulk fairly well.

Being a modern Audi, the cabin is extremely well executed, with amazing sport seats and the company’s trademark attention to detail. The base A6 will be replaced within two years, so this interior is a bit dated in terms of product cycle, but even then, the RS 6’s cabin cedes little to its competitors. And the RS 6 Avant is a great family car, spacious and confidence-inspiring, as are the more pedestrian A6 models.

Expensive, Thirsty, and Heavy

Is there anything not to like? Well, the RS 6 Avant is very pricey, at an equivalent of nearly $160,000 in Germany, and the 11-mpg average it returns when you push this beast hard is not good. Officially, it gets 17 combined mpg in the European cycle, and that’s a figure you can better, but the car just invites shenanigans—any good intentions waft out the massive exhaust pipes as quickly as you can downshift from sixth gear to second for a surprise pass on a back road.

There’s also the fact that the RS 6 Avant also feels a little too well behaved and detached. Blame the weight. The car is more than willing to play if you’re up for it, but you feel as if it has to work to go exactly where you want it. The previous RS 6, with its 450-hp twin-turbocharged V-8, felt more agile and, subjectively, just as fast as the current model, and it sounded more immediate than the current car.

One of the Greats

But charging through the twisties and gobbling up miles on the motorways, we think no other car in this league offers such an intoxicating combination of attributes. Behind the wheel, 120 mph is always just a few seconds away, and the speed can be scrubbed off right now if you need to make a good impression on a radar gun. Although V-10 engines may not be the thing in Formula 1 anymore, listening to the RS 6 at full throttle is one of the greater experiences in motoring. We just wish we could get it in the U.S.—and didn’t have to worry about those pesky speed limits everywhere else.

(BY JENS MEINERS, PHOTOGRAPHY BY MATTHIAS KNÖDLER)