Although exact build numbers of 1990s AMG cars are notoriously imprecise due to the independent relationship that AMG had with Mercedes, it is widely accepted that around one thousand AMG-fettled variants of the R129 SL were produced, and of those, between forty and fifty were SL 73 AMGs. When one considers that the SL500 outsold the SL600 by a ratio of 10:1 between 1993 and 2001, and that the latter is considered a rare car with just over eleven thousand units, it becomes apparent just how rare the SL 73 is; there are three times more Pagani Zondas in existence, a car with which the SL 73 shares its engine.

Indeed, from 1997 to 2001, AMG would, for those customers with the financial capability and desire to have something truly special, bore out the wondrous 6.0-litre M120 V-12 engine in the SL600 to 7.3-litres, upgrade the internals, and unlock in the region of 525 bhp and 750 Nm of torque. Thankfully, the brakes and active damping system were also fettled to cope with the extra power, and the result was a traction-restricted 0–60 time of 4.6 seconds and a top speed approaching 200 mph, if the 155 mph limiter was removed. In keeping with the understated gentlemanly appearance of the R129, the only items that give away its potency are the twin exhaust, a discreet body kit, small exterior badging, and AMG wheels.

Like many of the ultimate AMGs of this era, this 1999 example was delivered new to Japan and therefore benefits from the final facelift that Mercedes had unveiled at the 1998 Turin Motor Show, which included revised wing mirrors, colour-coded door handles, interior upgrades, and tweaks to the starting sequence on the car to include an auto-start function. It presents in fine condition, showing under 35,000 km on its odometer, and benefits from a suitably intimidating colour scheme of black with a black soft top and black leather interior, the latter of which boasts optional orthopaedic seats and the extended leather dashboard and door card option.

The R129 is already appreciated as a modern classic, and this incredibly rare SL73 is the absolute pinnacle of the range and unlikely to be repeated.