Based on
@Skd884's post, it's done zero miles in the last 16 months, not 8.
On the subject of running costs, 15k - 20k miles a year is going to be
very expensive. In addition to the fuel, I used to reckon on around 13k miles for a set of tyres on my W212 E63 Biturbo's at £200+ per corner, so that's between £950 and £1,250 a year, then budget also for brake pads and discs (around a grand for a front set, a bit less for the rears), and also the - almost inevitable - "big bill" for something that breaks on a 85k+ mile car.
Don't get me wrong, the W212 E63 is a hoot to drive (I still rate it as one of the best all-round cars ever) but running an older example outside of warranty on big annual mileages is going to be eye-wateringly expensive. I used to do 12-13k miles a year in mine so I do have a feel for these things.