Anyway, given The Patient is hors de combat, I went in with the Old Man to swap the old one for the virtually-identical new one this morning. The salesman (virtually a family friend now!) spent most of the time saying "there's no point in telling you how that works, because you know" and variations on the theme. Never was new car buying less exciting, as far as I'm concerned.
Seemed to cheer up the OM though, which is no mean feat in recent weeks, so maybe it was worth it.