Ok I was looking at specs and trying to figure out which to buy (s4 or a6, both '02) and I was confused by something. Basically the a6 2.7 and the s4 are identical in every aspect that would effect performance, the s4 is just 100 lbs lighter. Is this true? I know that it is the same engine and tranny but is there really no other difference? And if there isn't why wouldn't you just buy an a6 and have twice the room and more luxary feature and pay $3K less?

 

The S4's 2.7 has different internals and is tuned for performance where as the A6 is tuned for "luxury" or comfort. The S4 reaches peek power a lot sooner than the A6 meaning it has a much broader power band, which means the torque curve starts sooner and you have more power available regardless (to an extent) of what RPM you're at. The S4 also has stiffer and lower suspension, bigger brakes, and basically strong more performance tuned parts around the entire car.

To answer your question no they are not THAT similar, and the S4 is a hell of a lot faster than the A6. The main idea behind the S series is taking the bigger engine from the A6's or A8's (applying to the 4.2) and slapping them into a now over powered smaller car.

 

they dont even have close to the same transmission either. the S4 is much more aggressive. just because its a 2.7, does not mean its even in the same family.

 

or suspension way different also

 

If you check the gear ratios on the transmissions they are exactly the same.

 

Regardless I'm sure the 2.7 have stronger steels and clutches in the tranny