whats the difference between an RS4 and and S4, why is there an RS6 but not an S6? am i missing something? I probably am

RS models are more souped up powerful versions of the standrd S line.

RS4 has a hand assembled engine with much different tech, different suspension, drilled brakes, lighter weight, etc..... the RS cars are practically night/day different from the S cars.

the RS6 is no longer in production. it was based on the old A6 (B5 body). there was an S6 version of the old A6 and it continued to be sold until the new A6 (C6 body) came out. there will be a new S6 soon. there are unofficial plans for a new RS6 too.

B5 was the first A4. There will be both an S6 and an RS 6 for the new C6 body. Both cars will have an FSI V10, most likely with 5.5L of displacment rather than the rumored 5.2L, to keep up with or ahead of competition. The FSI V10 will likely produce 440 hp and 406 lbs/ft of torque in the S6 and 500 hp and 413 lbs/ft of torque in the RS 6. As with the RS 4 vs. the S4, the new RS 6 will be 300 pounds lighter than the new S6.

is that Audi's RS models will be 300 pounds lighter than identical S models. At least that was what some AW members are indicating.