Hi is this cover supposed to be over my air filter

 

yip, the bmw derv uses a similar filter must just be for extra filtration.

 

Cheers jay

 

Yep.

Very common in many cars these days with long service interval...IIRC the advised change interval for these is 60000 miles.

Some cheap and nasty non-genuine filters (like crossland...ECPs own brand) may not have the foam layer

 

That's what was getting me the mann ones didn't have the cover

 

Mann is a good filter and usually a OEM supplier. But obviously this one isn't, sometimes they do a choice of two quality levels (priced accordingly).

You get the same with pollen filters from the same brand; the cheaper ones are plain paper whilst the more expensive ones have a layer of absorbent charcoal.

 

Thanks ali