I learnt to drive in a HA van and BMW 2500 auto so not much difference there .
I think the BMW is where my love of big cars started. I have also had a Granada 3000, 4.2 jag, 4.2 Daimler sovreign
Couple of cars to add to the list to consider are the Jag XF and BMW 730D, sadly the beemer interiors to me seem sad and dated, the interior of the 300C is nothing to write home about looks wise either. Last time I was hankering after a BMW it was the 535i with the twin centre exhaust (X reg)
The merc is leading so far, on paper I need it to be capable of 50+ mpg, I need the extra width and comfort to help my health issues, I have damage in my legs which has knackerd my circulation and cause me quite a lot of issues, and limits me to a couple of hours max driving the car, but if I can jiggle about abit and keep changing my seat position then this helps my health issues.(this is where some cars with the hand brake down the side of the seat dont help.
Mark DTM made a good point, no good for short journeys, this is one of the reasons behind the better MPG and comfort, with the right car and feeling ok on a good day I can just jump in the car and nip to the coast, have lunch, bit of canoodling watching the sun go down and then when I get a bit bored go take a steady trip home via the country side or a blast down the M180/18
Intention is to keep at least 1 of the mig's, probably the 2.2 as a run about, maybe even one of the V6 motors as well.
Budget? good question, 7 years old, 70K max mileage, full electric leather seats and a sunroof is my target, seem some nice cars as low as £7000, don't know if I really want to spend that much, but then I don't smoke or drink, and anything that returns 40MPG+ on a run makes for a nicer car in the long run, if I want newer then I just need to save longer.
Only thing I have'nt looked into yet is the insurance, which might be a good idea before test driving any of them