If the non-hybrid V-8 appeals to you and you want a four-door there is presently only one answer: M850ix Gran Coupe. Same 523 hp 4.4 V-8 as the M550i. According to the U.S. EPA the G16 Gran Coupe has slightly more passenger and luggage volume than the G30. (I've no idea how valid these numbers are, though.) It's also a bit more expensive that the G30 M550ix was. There's the M5 of course, but at a still higher price point.
The current 8 series, including the M850ix, is in its last year of production, so I would avoid delaying too much if you go that route.
Car & Driver magazine was recently very impressed by the latest G60 540ix and the 550ex offers a bit more oomph in the same package, albeit with PHEV tech.
