840 Running Costs

I wonder if you could help me. I am 44 years of age and probably going through the sort of crisis that affects a lot of people around that age. For me, having had boring saloon cars ever since I passed my test, I have decided I need a 2 seater sports touring coupe. I have been looking for probably the last 12 months at the sort of cars that would realistically fit my needs of a comfortable long distance car, 6 cylinders or more and one that could possibly become a classic in it's own way in years to come. After lots of research, I am down to two cars. The Porsche 928 GTS or the BMW 840Ci. I am about 50-50 at the moment between the two, but recent research has revealed that the Porsche 928 has the potential to be pretty heavy on the running costs. Now, I certainly don't expect cars in this bracket to run on fresh air, but I have heard that at a minimum, I would be looking at 1000GBP to keep it in good order. That sort of figure would make me wince a bit, but some reports I've had put this figure closer to 2k which for the amount of driving I would be doing (as a 2nd car..) I would have to draw a line and say no.

So, my question relates to typical running costs for the BMW. Could anyone tell me what sort of costs I would reasonably expect on a per annum basis (just normal, typical costs, barring catastrophies). To give you an idea of what I would be lloking at buying, I am looking at a 96/97ish 840 with less than 50k miles and I expect my annual mileage would be less than 8k.

Many thanks in advance!

Ian