Air Conditioning....my XJS doesn't have it, my XJ6 did....but then again it's a bit pointless, especially in Scotland, just have to endure a hot steering wheel and sauna atmosphere for a few seconds until the windows go down.
More importantly, that button that comes with Aircon that gives you recycled air....I drove past a poo processing plant last week and realised I didn't have the magic "de-stinkifier button" any more, the smell was so bad I can't even hope to adequately describe it, it was like broccoli and old farts.