We'd reckon that there are some cars that most enthusiasts would like to see left well enough alone. Don't lower it, don't swap the engine, don't modernize the interior—just leave (or restore) it the way it came from the factory. The Mercedes-Benz 300SL is probably high on that list, seen by many as a perfect combination of aesthetics, character, performance, motorsports heritage, and craftsmanship. It's considered to be one of the "must-haves" in any high-tier car collection. That is, provided you can afford one.
Someone should have told this to Mercedes hot-rod shop AMG before it resto-modded eleven 300SLs starting in 1997. Unsurprisingly, the bulk of these conversions were done at the behest of the Royal Family of Brunei, who parked six modernized 300SLs in their cavernous garages. Between 1997 and 2009, five more of these anachronistic weirdos went under the knife for "qualified" customers.
Information on these AMG-ified Gullwings is scant, but according to a RM Sotheby's—who sold one back in 2014—the modifications are comprehensive. The venerable W198 chassis is retained, but altered to accept a 6.0-liter M119 V-8 found in contemporary AMG products like the E60 and R129 SL60, putting out around 380 horsepower. A four-speed automatic transmission manages this extra gumption, sending power to an updated rear axle lifted from the R129 Mercedes SL.
It handles like a 1990s Mercedes as well. Each AMG SL300 sits on a Bilstein sport suspension, backed up by C36 AMG brakes up front and W124 brakes in the rear. Modern, monobloc-style wheels are fitted to all four corners, and are presumably wrapped in performance tires that are light years grippier than the skinny rubber found on factory-fresh 300SLs. AMG futzed with the interior as well, adding leather-trimmed Recaro seats, modern safety belts, a 1990s-style AMG steering wheel, air conditioning, and an upgraded sound system.
If you think these modernizations hurt the value, though, you'd be surprised. Being an in-house AMG project lends it tremendous provenance, and since so few were created, values are roughly equal to an original Gullwing in very good condition. The BH Auction in Tokyo where this is crossing the block estimates this right-hand-drive example will hammer for somewhere above the $1.2 million mark.