If you want a practical Mercedes wagon, the German automaker currently sells the E-Class All-Terrain and the sporty E63 S Wagon. However, Mercedes has never built a luxury S-Class wagon. This left one client who wanted a more practical version of the German automaker's flagship sedan with no option but to commission a coachbuilder to build a one-off bespoke model.

In 1990, Hamburg-based coachbuilder Caro, which still operates today, brought its vision to life, creating an S-Class wagon for one very wealthy client. Caro's creation is based on a 1990 Mercedes 560 SEL with taillights and a rear deck taken from a Mercedes W124 wagon with "minor modifications of superb quality made to ensure fitment."

The cargo area is also built using components sourced from the W124 wagon with additional modifications made by the coachbuilder. However, Caro was unable to utilize the W124's rear windows, so the coachbuilder fitted custom rear windows instead.

Modifications were also made to the roofline, C-pillars, and rear quarter panels to maintain the SEL's proportions and styling when coupled with the new rear deck. The level of craftsmanship is so exquisite that Caro's custom S-Class wagon could easily be mistaken for an official Mercedes model. When it was new, Caro's Mercedes S-Class Wagon cost over DM 337,000 ($209,040 according to current exchange rates) including the cost of a new 560 limousine and the wagon conversion.

The S-Class wagon is finished in Pearl Black metallic with a black leather interior. Being based on a 560 SEL, power is sourced by a 5.5-liter V8 generating 300 horsepower, which is sent to the rear wheels through a four-speed automatic transmission.

If you fancy owning this one-of-a-kind luxury S-Class wagon, the coachbuilt car is being sold at RM Sotheby's Arizona auction this month, where it's expected to fetch between $30,000 and $40,000 with no reserve. This could be your only chance to own a luxury S-Class wagon because Mercedes isn't planning to build a more practical version of the current S-Class.