E65 7 Series Running Costs

[thatguy11]

So for some reason I've gone a bit mad and decided I desperately want an E65 7 Series sometime relatively soon, most likely a 735i or 745i.

Does anyone know how ruinous these things are to run or are they surprisingly cost-effective? I'd absolutely love a big barge and the 7 series is massively more appealing to me than a similarly aged S Class/A8, I just hope it's not too catastrophically expensive!