I suggest getting an undercarriage wash once a year at the end of winter if you live where salt is used on roads, to reduce rusting away of your chassis. Still just once a year so you can keep feeling pretty smug about not washing, but, you get most of the benefit of the wash, which is longer rust free body life.

It has quite an impact -- this is why it's much harder to find intact cars older than a couple decades or so in the north as opposed to the desert west.

> Rain and the occasional wet rag is good enough for a depreciating asset.