Thinking of Buying

The 840 Ci Sport is definitely the right one to get.  It has the 4.4l V8 which does not have the Nikasil problem of the earlier 4.0l V8 and slightly less complex than the V12.  Also has all the M-tech bodywork and mirrors.  You get a little less power than the 850 but it really does not matter (the points add up just as quickly!)

I got the Rac to inspect mine (bought last Sept, also 97R, but 64k miles).  Don't buy it if any of the electrical bits don't work (and there are many of them).

It isn't cheap to run with a >£50 tank fill.  I have been towed twice for basically the same problem (a blown heater valve, and subsequent blow out of a weakened heater pipe).  Loading onto a low-loader can be a problem as the skirts have very low-ground clearance.

When the sensors go haywire (once in 6 months - oddly enough the temperature sensor went sour), then even BMW dealers have problems diagnosing them, although any good independent can do the servicing.  I bought a Peake Research R5/FCX-II Code/reset tool of my own as some garages do not have 8 series on their diagnostic systems (I am also a gadget freak so this satisfied other urges).

Despite a few problems, I do not regret buying the car at all - it is fabulous and made even my dearly beloved 635 I traded in seem like a smelly old boneshaking penny farthing.