Just had my car serviced and requested a full service as I only had the oil changed about 10 months ago and the plugs about 18 months ago. Audi said that I do not need to change the spark plug until 80k, also the same for the air filter. my question (maybe I am missing something) but the manual states that I should change the plug every 40k using unleaded or 15k using leaded, I use Optimax 90% of the time so should 40k be OK or should it be 15k. One last thing, the air filter should this not be changed at least every year...? my previous car was the Cav 4x4 Turbo (petrol) and everything was serviced at least every 4-6 months to keep it in good health.