In the grand pantheon of automotive design, few cars command a room quite like the Mercedes-Benz 126 series SEC. Introduced in an era when unyielding presence and road-going authority required zero apology, the C126 represented the absolute pinnacle of luxury grand touring.
Under the steady hand of design icon Bruno Sacco, the SEC is defined by its sweeping bonnet, pillarless side profile with frameless glass, and razor-sharp, uncluttered surfaces. It was was reportedly Sacco’s personal favourite – and arguably his greatest triumph.
During the 1980s, when AMG was still an independent tuning house in Affalterbach, engineers began boring out Mercedes V8s to unleash the beast within. But the SEC’s transition from high-society cruiser to road weapon came about when AMG unveiled its famed Widebody. Featuring aggressively flared arches that broadened its stance without corrupting Sacco’s clean lines, the SEC developed a new level of toughness.
The ultimate evolution of the concept reached its peak where few expected a two-tonne luxury coupé to compete: the racetrack. Engineered for FIA Group A competition, the AMG 500 SEC shed substantial weight, replaced its automatic transmission with a dog-leg manual racing gearbox, and extracted roughly 460 horsepower (343kW) from its tuned V8. Its place in motorsport folklore was secured at the 1989 24 Hours of Spa-Francorchamps, where a pair of black SECs clad in König-Pilsener and BOSS liveries battled for victory at the hands of touring car giants Klaus Ludwig and Hans Heyer.
Nearly four decades later, German restomod specialist Mechatronik is opening a new chapter in this story. By merging classic 1980s design with modern manufacturing technologies, the Pleidelsheim-based firm has created the M SEC—the third model in its New Tech series.
Re-engineering an Icon for a New Era
The M SEC is the culmination of a four-year development programme designed to honour the SEC’s heritage while introducing contemporary level performance. Rather than replacing the car’s beating heart with an electric drivetrain or generic crate engine, Mechatronik paired the C126 chassis with AMG’s most celebrated modern power plant—the naturally aspirated 6.3-litre M156 V8.
Created to celebrate Mechatronik’s 30th anniversary in 2027, production of the M SEC will be strictly capped at just 30 handcrafted examples worldwide. Each build begins with a customer-supplied donor Mercedes-Benz SEC, which undergoes a complete transformation tailored specifically to the owner’s specifications.
Mechatronik employed state-of-the-art engineering tools during its four-year development cycle to ensure the M SEC retains its long-distance touring grand tourer attributes, while delivering enhanced corer-carving abilities. High-precision 3D scanning and CAD modelling allowed engineers to integrate modern components into the 1980s architecture without compromising structural integrity.
Built From Bare Metal Up
The ground-up re-engineering effort goes far beyond a conventional restoration, beginning at Mechatronik’s Pleidelsheim manufacturing facility, 30km north of Stuttgart. Here, the donor vehicle is stripped down to the last nut and bolt, with every original component inspected and catalogued. The bare steel bodyshell is then subjected to a chemical paint-stripping bath, removing decades of paint, undercoating, and surface contaminants to reveal raw, unblemished metal.
The bodyshell then undergoes a Cathodic Dip Coating (KTL) process to protect against corrosion, before the hand-building phase begins in earnest. To maintain absolute consistency and quality control, a single dedicated technician oversees each vehicle throughout its assembly, taking primary responsibility for key build stages.
Widebody-Inspired Carbon Fibre Body
While the M SEC retains the unmistakable silhouette of Bruno Sacco’s original design, its exterior design is further enhanced by a bespoke carbon fibre body kit developed specifically for the M SEC.
Rather than using the lightweight material purely as an ornamental trim, Mechatronik has used it for key structural and exterior panels—including the front apron, rear bumper, front wings, side skirts, side cladding, and rear spoiler. The result not only trims weight but sharpens the vehicle’s aggressive stance.
The carbon components can be left exposed, finished in tinted clear coats, or sprayed with fine layers of translucent paint that allow the underlying carbon weave to shimmer under direct light.
When it comes to the paintwork itself, customers can choose from period-correct Mercedes-Benz paint codes or specify bespoke modern shades.
The Atmo V8 Lives!
Under that long, sculpted bonnet lies one of the greatest naturally aspirated engines ever built: the 6.3-litre AMG M156 V8. Renowned for its immediate throttle response, linear power delivery, and thunderous acoustics, the quad-cam V8 produces 500hp (368kW) and 630Nm, delivering effortless acceleration and massive overtaking reserves.
Power is sent to the rear wheels via an AMG SPEEDSHIFT 7G-TRONIC automatic transmission, recalibrated to offer lightning-fast shifts during spirited driving while retaining smooth shifting for relaxed motorway cruising. Traction and cornering stability are managed by a multi-plate limited-slip differential on the rear axle.
Spent gases pass through a custom-developed stainless-steel exhaust equipped with sports catalytic converters, designed to showcase the V8’s high-rpm bark while reducing cabin drone during long-distance touring.
Chassis, Wheels, and Braking
To manage 500 horsepower, the M SEC sits on an individually tuned chassis with adjustable suspension and high-performance brakes. Drivers wanting a more track-focused setup can specify the optional GT Package, which incorporates stiffer suspension calibration and lightweight components for enhanced precision.
Connecting the M SEC to the tarmac are 19-inch wheels styled after iconic 1980s designs. The Mechatronik Aero is a modern reinterpretation of the legendary monobloc design from the AMG Hammer era, while the Cross-Spoke Mesh wheel is a classic multi-spoke design drawing inspiration from 1980s motorsport.
Both options are wrapped in ultra-high-performance Michelin Pilot Sport 4 S tyres (255/35 R19 front and 295/30 R19 rear), with track-ready Michelin Pilot Sport Cup 2 tyres available for sportier configurations.
Modern Functionality Wrapped in Classic Luxury
Inside, the M SEC preserves the timeless ergonomic layout of the C126 while bringing materials and electronics into the 21st century.
Owners can tailor every interior surface, selecting from premium leathers, custom contrast stitching, high-grade carpeting, and Alcantara headliners. Dash and door veneers can be finished in traditional Mercedes-Benz woods—burr walnut, Zebrano, or original birch—or specified in lightweight exposed carbon fibre. Seating options range from re-trimmed factory seats to supportive sports seats or lightweight bucket units.
Directly ahead of the driver sits a custom-engineered instrument cluster that retains classic analogue needles and typography while integrating a high-resolution digital display that provides real-time telemetry, engine diagnostics, and driver data.
Audio & Connectivity Options
To maintain period accuracy without sacrificing modern connectivity, Mechatronik offers two distinct head unit choices: the Mechatronik Radio Classic which is a traditional 1-DIN head unit designed to mirror 1980s Mercedes factory radios but which features DAB+ digital radio, AM/FM tuners, and Bluetooth; or Mechatronik Radio Connect which features a 1-DIN frame housing a 6.38-inch LED touchscreen which provides wireless Apple CarPlay and Android Auto, DAB+ radio, and optional integrated front and reversing camera displays.
Audio enthusiasts can also upgrade to a bespoke 1,560-watt high-end sound system developed specifically for the C126 cabin with 10 speakers, 3 subwoofers and driven by an 18-channel digital amplifier.
Let There Be Light
The SEC’s lighting technology has also been completely overhauled with full-LED headlamps incorporating bi-LED projector modules housed within the original rectangular lamp signature.
The headlights deliver a massive improvement in night-time visibility over 1980s halogen units with the internal housings able to be painted in the vehicle’s body colour.
Slippery At Any Speed
During its four-year development, the M SEC underwent extensive wind tunnel testing with engineers optimising air channels, underbody airflow, and carbon aero elements to achieve a lower drag coefficient than the original production C126. The result improves engine cooling, reduces wind noise, and enhances high-speed stability on the Autobahn.
Proven on the Nordschleife
Mechatronik subjected multiple M SEC prototypes to gruelling real-world test regimes to validate the vehicle’s durability. This included prototypes being driven in extreme summer heat and frozen winter conditions to test thermal efficiency, cold-start reliability, and climate control performance.
The M SEC was also track tested with high-speed dynamic chassis tuning conducted on the Nürburgring Nordschleife and the Hockenheimring, pushing the suspension, carbon body structure, braking systems, and engine cooling to their absolute limits.
Extensive chassis dynamometer runs were also conducted to ensure consistent power output across the entire rev range, while thousands of kilometres on mountain passes, country roads, and motorways refined its everyday ride quality.
The New Benchmark for Restomods
With only 30 individually configured examples being built for Mechatronik’s 30th anniversary in 2027, the M SEC is a masterclass in modern automotive restomodding. By respecting Bruno Sacco’s timeless proportions and infusing it with 500 horsepower of naturally aspirated V8 grunt, Mechatronik has created a true high-performance Gran Turismo that stands as a fitting tribute to Mercedes-Benz and AMG history.
