8-series

Dear all

I've read the various threads about which is the better car [840 vs 850
(ignoring the CSI)] and whilst these are no doubt informative I do
wonder whether they may be a little out-of-date.

So, I ask (previous owners?) that, with the benefit of hindsight, which
really is the car to own!

The points I'm really interested in are as follows:

1 - economy: are they similar or radically different?

2 - robustness: which of the two engines is the more "bullet proof"

3 - total cost of ownership: are parts for one significantly more
expensive than the other? What annual bill would I be looking at to
cover maintenance?

4 - when buying a car, any particular things to check?

Many thanks in advance

Griff