After the back-breaking gymnastics required to change the Microfilter on the E32 the E38 ones (yes, there are two) is dead simple. We hardly need a 'How to' but it's good to know what to expect so:

Buy only BMW's Microfilters, I got a pair from EuroCarParts and they didn't have the little securing tabs....and weren't all that good a fit, still, you live and learn.

Open the bonnet and undo a single screw on the filter cover:

The cover hinges on the inside to reveal the Microfilter

The filter (including remains of dog) pulls out using the tab from the outside edge:

Mmmm....seem to have a stowaway in there:

Old filter out......new filter in....make sure you get all the foam around the filter correctly in the aperture:

Screw the covers back on and that's it.....not really worth a cup of tea....