Sheesh, the Sultan of Brunei's Wikipedia entry sounds like it's been edited by Robin Leach. Suffice it to say, that when you spend upwards of $4 billion on 3-5,000 cars, your garage is going to contain quite a few sweet custom wagons.
His Majesty's fleet of Ferrari 456 station wagons have already been featured here on DT. It's the tip of the touring, estate, shooting break, station wagon iceberg.
Jalopnik's got a highlight reel of the Sultan's car collection, including a few wagons; there are hundreds more photos at Basman007's Brunei Gallery on Supercars.net. Here are some highlights from the highlights, starting with the insane 1990 Bentley Turbo R Sports Estate above, which has all-wheel-drive [in reverse and first gears only].
This is a Bentley Val d'Isere, which also has an AWD system. Does that mean the Turbo R above was converted by Robert Jankel, too? Once again Bentleyspotting has an extensive post on the Val d'Isere, which came in long- and short-wheelbase versions.
Obviously, this one is not owned by the Sultan of Brunei, but by his cousin, the Hamburglar of Brunei.
The estate adaptations of the 1994 Bentley Java concept car, I will leave for you to discover on your own.
The 1990's W140 S-Class was the pinnacle--or nadir, I guess--of Mercedes' unchecked trees-not-the-forest, over-engineering. Those silly double-paned windows, and those little antennae for backing up--because the rear of the car was totally invisible to the driver--and they all weighed like six tons, so heavy they needed new tires every 10,000 miles.
All of which only tempers my admiration for the S73 Touring, an AMG-modified S-class wagon with a 7.3L V-12 designed for the Pagani Zonda supercar shoved under the hood. Apparently, His Majesty ordered up a Sultan's Dozen  before cutting back to a Sultan's Half Dozen . So prudent. Since the W140 and the Pagani only overlapped for a year, I'm guessing these are from 1999.
A garage fit for a kind: the best of the Sultan of Brunei's collection [jalopnik]
images via Basman007's Brunei Galleries [supercars.net]
Bentleyspotting, just what it says [bentleyspotting.com]
Previously: the Sultan's insane Ferrari 456 station wagons