maybe the older M60 and before V8 had problems , you know how muck sticks .
I have a M62 TU V8 X5 and a M62 V8 740 i . they can wear prematurely , just yer luck I suppose as any engine can suffer same . how many miles do you intend putting in a car anyway .
my X5 indicates 20 - 21 mpg . the 740i indicates 22-23 mpg . both cars doing the same running mixed rural / city driving .
rural only driving hill and dale will return average 15% more mpg .
city only driving is 17-18 mpg .
the insides of the exhausts are clean and shiny , not at all like the filthy diesels .