The year is 1999. European governments don’t appreciate big engines and so tax them to near-extinction with a displacement-based system. High fuel prices don’t help. But when did any of that stop AMG from boring and stroking? Enter the SL73, the 7.3-liter V-12 roadster based on the 6.0 SL600 Mercedes-Benz R129. With 518 horsepower and 553 lb-ft of torque, it’s no wonder why Sauber Group C fan Horacio Pagani went for the M120 engine when he came up with the Zonda C12 S, the Zonda F, the Zonda Cinque and the Zonda Tricolore.
Since then, at least twice as many Zondas have been built as SL73s. Not that anybody could agree on how many SL73s were made, anyway. Between 1993 and 2001, SL500s outsold the SL600 by a ratio of roughly 10:1; SL600s then had to go to AMG, along with 50,000 Deutschmarks, in order to be turned into SL73s. Auction house RM Sotheby’s estimates between 40 and 50 SL73s were built. Other sources go as high as 85; rumor has it that 27 of those went straight to Brunei, which would explain some of the disparity.
What’s for sure is that this final facelift fourth-gen SL from 1999 did not. It went to Japan instead, complete with all the titanium engine bits, the lacquered wood, and the promise of 186 mph. Yet to keep the low profile that Mercedes-Benz preferred at the time, AMG only added a subtle body kit, twin exhausts, and its signature wheels to the SL73, while upgrading the suspension and the brakes. Without the badging, would that be enough to distinguish it from an AMG-tuned SL600?
Showing under 22,000 miles on the clock, this triple-black SL73 will go under the hammer at RM Sotheby’s London auction on October 24, complete with the optional orthopaedic seats, as well as the extended leather dashboard and door card option. And while the SL73’s no Zonda, it won’t cost you Zonda money, either. Then again, Pagani has wizarded 789 horsepower out of this engine since 1999, so you know what to do.