I have been very happy with my silver E39 540iA......its loaded with all the goodies - 18" Alpinas, Carin522 sat/nav, white lenses, Swichtronic and so on. I think that, with one proviso, the 540 is a great car.
My reservation is that it is a dull drive. Sure, you feel classy and ever so rich when you cruise around the streets, and I never found it wanting for performance in absolute terms. Its just that what it does, it does ever so politely...if you get my drift.
Now, I was driving past my local BMW dealer and spotted a new M5 in what I think is called Silverstone blue....a light metalic colour. What a sexy little beast. So I turned in to the forecourt, spoke to a salesman, and, 10 minutes later was given the keys to test the beast.
Initial impressions compared with the 540? Well, much more direct and better weighted steering, a symphony of an exhaust noise and performance in an entirely different world from my 540. Outstanding.
Am I going for it..........you bet.