Ok, this didn't go to plan.
Fate (a.k.a my wife) stepped in and suggested that, as I was going to be spendng that sort of money, maybe I should consider more "age appropriate" alternatives. Within the space of 24 hours, I had seen, test-driven and bought a Mercedes SLC200 for not a whole lot more money - manual (I didn't agree with critics' review of this at all), fully loaded and with just 2k miles.
I'll pop into the forum occasionally, to see what might have been.