Should my 98 have a cabin air filter and possibly ones for the heater, perforated leather seats too? I cant seem to find ANYTHING on Amazon, and thats where I usually buy these odds and ends from. But they show no record of such items for my car. No filters for our cars?

 

'98 model X308's were not fitted as standard with cabin filters but could be fitted as an accessory which also meant the dealer had to re-programe the body computer to adjust fan speeds to compensate for the filter fitment.
These were fitted in the scuttle area at base of screen under the plastic cover below wiper.
No extra filters were needed and there were no aerated seats accessories available for this model.
This didn't come in until the release of the X350.