Jools,
       don't judge the book by it's cover. There may be some vehicles at the Airport that come under your category as " old bangers" but most of them that I have seen parked seem to be in good/fair condition other than the dust on them.
Also is it worth the risk to return and find the car moved or impounded and before you can get it back the authorities want to see documents for proof of ownership then maybe tax,mot and insurance and you cannot produce.I would like to think the majority can produce if necessary, and if not, it's a long walk home!!