Frankfurt 2011: Audi Unveils The S6, S7, and S8

Some manufacturers would choose to space their introductions of performance cars out a bit.  Maybe one or two at Frankfurt, and another at Detroit.  Not Audi - they're bringing four all-new S models to the Frankfurt show this fall: the S6, S6 Avant, S7 Sportback, and the S8.

The big trend with performance cars is obviously engine downsizing.  The BMW M5 went from 5.0L and ten cylinders to 4.4L and eight (gaining two turbos and 60 horsepower or so in the process.)  Mercedes' AMG Division has shrunken their thundering 6.2L V8 down to 5.5L, but added twin turbochargers.  The new Focus ST is dropping a cylinder and gaining direct injection for more power.  This comes from a seemingly contradictory pair of needs: meeting rising fuel economy average numbers, while still offering heaping mounds of power to well-heeled enthusiasts.

So like many others, Audi is dropping cylinders.  In fact, this is true across the entire A6 range.  The previous generation (at least here in the US) had a standard V6 and an optional V8; the new A6 has a standard turbo 4, and an optional supercharged V6.  So while the previous S6 packed a 5.2L V10 (derived from the Lamborghini Gallardo/Audi R8 5.2 motor), the new S6 lowers the cylinder count to eight, and ups the turbo count from zero to two.

This new engine makes some familiar-sounding promises.  Namely, no sacrifice in overall performance, increased low-end torque, but less consumption and friendlier emissions - much like the new turbo V8's from BMW and Mercedes.  It's smaller, though - at 4.0L it's pretty light on displacement compared to the E63 and M5.  The motor was co-developed with the Bentley division (weird to call it that) and features all the expected modern technology - twin low-inertia turbochargers, variable displacement (the nicer way of saying cylinder deactivation), high-pressure direct fuel injection, aluminum construction, etc.

This new engine will be available in two states of tune, under the hood of the Audi S6 sedan and Avant (wagon), S7 Sportback, and the larger S8 sedan.  It will also be found under the hood of an upcoming "base model" Bentley Continental GT in the near future.  In the S6 and S7, it generates 420 horsepower and 406lb-ft of torque over a wide range from 1,400-5,300rpm.  This compares pretty well with the old 5.2L V10 in the S6, which made 435 horsepower and 389lb-ft of torque.  Performance is pretty similar as well: 0-60 in 4.8 seconds for the S6 sedan and S7, 4.9 for the S6 Avant.  Fuel economy is supposedly 25% better overall than the old engine, coming in at 24.3mpg (US) combined for the sedan and Sportback, and 24.0 for the Avant.

In the larger S8, there's a considerably higher amount of poke available: 520 horsepower, and 479lb-ft of torque from 1,700-5,500rpm.  Despite the extra heft, the S8 has no problem accelerating like a bat out of hell: 0-60 in 4.2 seconds seems adequate.  All four  models are limited to 155mph in typical German fashion, although I imagine if you hand a wad of Euros to Klaus at the factory he can fix it.  Despite the extra hundred horsepower and more weight, the S8 still returns an average of 23.1 mpg US combined, which is pretty good compared to the previous S8's 17.8 and 70 less horsepower!

Obviously, all four cars send power to all four wheels.  They have the latest and greatest Audi drivetrain tricks as well:  a self-locking center differential, 40:60 static torque distribution, an optional torque-vectoring rear differential, Audi Drive Select, etc.  The S6 and S7 have a 7-speed twin clutch automated manual transmission, while the S8 uses a smoother 8-speed Tiptronic automatic transmission, more akin to the S8's luxury rocket mission. Carbon-ceramic brakes are an option on all four; I would love to see an S8 late-braking into the Corkscrew at Laguna Seca.

One wonders if Audi will simply install the S8's engine tune into the S6 and S7 models for the inevitable RS6 and RS7, while there are surely some internal differences, I'd imagine most of the power disparity is due to the state of tune and boost levels.  So while the S6 isn't nearly as quick as some of it's competitors (it would not know which way the 556bhp Cadillac CTS-V went), the problem will probably be easily resolved with an ECU reflash, should you be tempted to modify it.

The only question remaining is pricing, which will likely be announced closer to the model's market debuts.  However, if it's like the previous S6 and S8 models, it will likely be lower than existing direct competition - E63 AMG and M5 for the S6, S63 AMG and Alpina B7 for the S8 - to make up for the performance deficit, and leave headroom for RS models.