Renntech’s SEC V12 Sledgehammer Comes With A Gearbox Benz Never Offered

Update: Renntech has released a fresh set of higher quality renderings of its upcoming Mercedes SEC V12 Sledgehammer, though that is not what caught our attention in this latest teaser. The real surprise lies in what the company revealed about the powertrain, as this retro modern creation pairs its large capacity V12 with a seven speed manual gearbox.

In the often rarefied world of Mercedes-Benz tuning, few brands do it better than Renntech. For more than 35 years, the American brand has been building and upgrading Mercs, and it has just previewed one of its most ambitious projects to date.

Read: RENNTech Gives Us All The Details On The S76R’s Bored And Stroked 7.6-Liter V12

This new creation is called the Renntech SEC V12 Sledgehammer, a nod to the Hammer moniker applied to numerous AMG-modified Mercedes-Benz models of the mid to late 1980s.

The car will be based on the iconic C126 SEC and built as an homage to the Mercedes M120 naturally aspirated V12, the engine famously used in the CLK GTR and Pagani Zonda. Renntech has reengineered this powerplant, increasing its displacement to 7.5 liters, which allows it to produce 650 hp and 650 lb-ft (881 Nm) of torque.

To ensure the SEC V12 screams just like a Pagani, Renntech has developed custom equal-length headers for it. Other upgrades include comprehensively reengineered with forged internals, CNC-ported cylinder heads, advanced intake and exhaust systems, equal length headers, and bespoke calibration.

A 7-Speed Manual Gearbox

Surprisingly, rather than pairing this big displacement V12 with an automatic, Renntech has opted for a 7 speed manual gearbox driving the rear wheels. The company has not disclosed further details, yet seven speed manuals are rare territory.

Only a handful of production cars have ventured there, including the Corvette C7, certain Porsche 911 variants, older Aston Martin Vantage models, and, crucially, the Pagani Huayra, which uses a gearbox from British engineering firm Xtrac. That connection matters because the Pagani also relies on a Mercedes AMG sourced V12.

Unique Bodywork For A Unique Benz

Renntech plans to cap production of the SEC V12 at just 12 examples worldwide, each designed to look significantly more aggressive than your typical C126 from its era. Renderings released by the firm show the car outfitted with a bespoke body kit, featuring revised front grilles, a distinctive hood, and uniquely shaped front and rear quarter panels that sit considerably wider than standard.

The custom bodywork has also enabled Renntech to add bespoke forged 19-inch wheels to the car, sitting over a set of beefed-up aftermarket brakes. The rear will also be customized with a new bumper, diffuser, and a prominent lip spoiler. Not only do these new parts transform the grand coupe’s appearance, but Renntech says they improve aerodynamics as well.

Interior images haven’t been revealed yet, but customers will have access to bespoke cabin configurations. A full range of materials and finishes will likely be on offer, allowing each buyer to tailor the space to their tastes.

Pricing remains unannounced for now, though Renntech has confirmed that the first customer car is scheduled for completion in 2027.