I've just noticed my undertray is gone. Almost certain it was on there. It's a Kombi. Everything looks really clean underneath where it was so looks like it disappeared recently. Are these things known to just fall off?
Generally not quietly .......
I've lost the under trays on a 2002 Passat TDI and 2013 Skoda Superb Estate.
I picked the Passat up from a service and was on the M26 when the front edge of the tray dropped. The wind force pulled it down and it swivelled on the remaining fastening and got wedged under my nearside front wheel. The whole experience sounded and felt like I'd run over something big. That was easy to strap up because it was still held on by a bolt at the back - webbing strap from passengers door across the bonnet, under the tray, back up the other side, across the bonnet again and pinned the end of the strap in the drivers door. Drove to the dealer where they tried to charge me £120 for the fixings kit and replacement tray.
Skoda was less exciting, driving from Devon to Kent and I could hear a scraping noise every time I went over a bump. This time it was dropped at the rear. It was pretty scuffed up by the time I got there (night driving) and I had no tools or ramps so I paid a man to take it off completely, ordered a new one from eBay and fitted it myself back in Devon.
In short, you would have noticed it falling off.
I presume that as you didn't notice it going, that it fell off silently into the hands of someone that wanted one.
ETA: Passat was in 2003, Skoda was last October 2024.