Very interesting article. Thanks BMW_Dude

Wow, an intriguing find indeed, thanx for posting! Also, thanks to PC for the clear and informative explanation!

It's important to understand how the quattro drivetrain in the S3 influences how they measure power compared with the quattro drivetrain in the RS4.

If you read through the website, you'll see that the type of AWD system determines the test procedure. For a Haldex coupling equipped car like the S3, the front axle is deemed as being the primary axle and so, power and torque will be measured at the front wheel hubs only. Hence the S3's very good power accuracy, as is with many FWD cars that lose less power than RWD cars. So-called AWD cars that were engineered from conventional transversly engine mounted FWD cars typically use this Haldex coupling arrangement that directs 100% of power to the front axle and only when slip occurs at the front will drive be directed to the rear wheels.

With a true AWD car the wheel hub dynamometers are are attached to all four wheels as power is directed permanently to all four. This obviously results in a significantly reduced power at the wheels.