A guy at work runs an older 7 series and loves it. Actually quite reasonable to service at a specialist. Just oil, filters and spark plugs – dealer servicing charges of £300+ are a joke. There are plenty of specialists out there who know more than dealers and can give you advice about the best way to run these things.
Obviously if something substantial like gearboxes and engines start blowing up then it’ll cost you, but brakes/suspension and other parts can be purchased for decent money and there will be plenty of breakers out there for 2nd hand parts.
I’ve often been tempted by used Audi A8’s / VW Phaeton’s. £80k + cars that can be had for less than £10k after 5yrs with decent mileage. Just a shame they don’t do these big barges in estate versions.