Mercedes-AMG specialist Renntech from Florida, USA, has created a limited series of just 12 examples of a super coupe based on the Mercedes 126 SEC, equipped with an in-house modified V12 derived from the famous M120 engine. Its name: Renntech SEC V12 Widebody.
Renntech, based in Stuart, Florida, and founded by Hartmut Feyhl in 1989, is recognized in the USA as a leading Mercedes-Benz specialist. Hartmut Feyhl himself is considered by many to be one of the foremost authorities in the United States on Mercedes-AMG tuning, thanks to his extensive experience with the AMG brand.
Feyhl worked for 12 years at AMG Germany as a development engineer and previously served as technical director of AMG’s North American division.
Renntech is known for modifying Mercedes models with a focus on very large-displacement engines and top-tier performance. One such example is the SEC V12 Widebody Sledgehammer, a super coupe based on the Mercedes C126 SEC.
Essentially, it is a coupe based on the Mercedes C126 series that features under the hood a unique V12 engine that was never available from Mercedes or AMG (which was independent at the time). Considering its displacement and power output, the nickname “Sledgehammer” fits this supercar perfectly.
This model pays tribute to the famous naturally aspirated M120 V12 engine used by Mercedes in its flagship models during the 1990s and 2000s. It debuted in 1991 in the 600 SE/600 SEL versions of the S-Class W140, and later in 1992 in the SL 600 R129.
From this 6.0-liter naturally aspirated V12, which produced 408 PS in the 600 SE/600 SEL, Mercedes-AMG developed several versions: the E70 AMG used in the SL 70 AMG, the E73 AMG found in the SL 73 AMG, and the M297 engine created exclusively for the Mercedes CLK GTR.
Versions of this engine were also used in various Pagani Zonda models.
Renntech did not adopt any of these derivatives but instead built its own version, increasing displacement from 6.0 liters to 7.5 liters. Without using forced induction, this massive engine produces 669 PS and 881 Nm. These figures are astonishing, especially considering that at the time the Mercedes S-Class W140 with the 6.0-liter M120 V12 produced 408 PS.
Meanwhile, the Mercedes C126 and W126 were never offered with V12 engines. The most powerful version in the C126 range was the 560 SEC, which featured a 5.6-liter V8 producing 299 PS. AMG-tuned V8 versions based on the C126 produced at most 385 PS.
The American company has not disclosed many details about the modifications, stating only that the SEC V12 Widebody features optimized cooling, improved high-speed stability, and enhanced aerodynamics. The superior stability comes from wider track widths, with flared wheel arches making room for specially designed five-spoke forged wheels.
Despite the widened fenders, the Renntech SEC V12 Widebody looks relatively restrained and not as aggressive as some builds from competing tuners. However, it does include several aerodynamic elements that also serve a functional purpose.
The aerodynamic package includes a larger lower air intake, a fairly discreet rear spoiler, slightly flared side skirts, and a diffuser framed by two pairs of exhaust tips.
The Renntech SEC V12 Widebody Sledgehammer will be produced in a strictly limited series of just 12 units starting in 2027. Each classic C126 chassis undergoes a complete restoration and is reinforced to handle the enormous power output.
