Interesting.........I do oil changes on my bike and the 325i, and make very little mess. In fact, I do these in the appartement car park, which generally isn't endorsed in the guidelines but since I've never made a mess. I put some cardboard or newspapers around the oil pan, have a fairly good idea of how the oil is going to spurt out when opening the drain plug, and it's all good.
The 3er is a b*tch to work on though......the lowered sport suspension offers no space even when using a special floor jack.