My friend Ian has the S8 V10, really nice car but $$$ to maintain ; my other mate Terry has the S6and generally most RS models through out the years
Cat sensors , t chains, tensioners , oil pumps and most bloody jobs need the engine out ; 20 hrs labour and it cannot be rushed , @ 7K euro; they are eye watering to expensive to fix, he also said is you have the ceramic discs, they need replacing every 7 years due to sun exposure @ 4-5K , most get a steel setup and flog on flea bay
Another of Terrys friends treated himself to a new TDI 3.0 , he went in for a normal service, car was 3-4 years old at this stage and 60K KM ; audi said the tensioners needed replacing , engine out @ 8K euro with new parts
Single Supra ownership is cheap in comparsion