You'd be surprised, nowadays it's about 50/50 in terms of volume. 2.0s, 2.5s, VR6s, have the filter underneath, where as all the 2.0T (TSI, for sure, FSI IIRC is underneath) and Diesels are above. We're an ex saturn dealership too so we get a lot of GM ecotecs in the door (not that it pertains...