Gordon Murray Automotive has unveiled the GMA T.33 Spider, a roofless version of the T.33 Coupe featuring a 3.9-litre Cosworth V12 that revs to 11,100 rpm. Limited to just 100 examples, it is one of the most technically ambitious naturally aspirated supercars of the modern era, and one of the last to prioritise a free-breathing, high-revving engine above all else.
Engineering the Perfect Open-Air Supercar
The T.33 Spider was developed in parallel with the coupe from the earliest stages, not reverse-engineered from the closed car after the fact. This allowed GMA's engineers to redesign the ultralight carbon fibre monocoque for greater torsional stiffness to compensate for the absence of the roof structure. The result is a roadster that does not compromise the structural integrity or dynamic precision of the coupe, a common failure mode in convertible supercar programmes. Dry weight is 1,108 kg (2,443 lbs), with aerodynamic downforce of over 150 kg at 150 mph.
The Cosworth V12: Why 11,100 RPM Matters
The GMA.2 engine is a 3,994 cc all-aluminium naturally aspirated V12 designed in partnership with Cosworth. It produces 609 hp with a peak torque of 333 lb-ft (451 Nm), with 75 percent of that torque available from just 2,500 rpm and 90 percent from 4,500 to 10,500 rpm. The 11,100 rpm redline is not a marketing number. It is a direct consequence of the short-stroke architecture, titanium connecting rods, flat-plane crankshaft, and individual throttle bodies that Cosworth developed to GMA's specification. The engine sounds nothing like a turbocharged motor; the power delivery is linear, and the soundscape rises continuously through the rev range in the tradition of Ferrari's finest naturally aspirated V12s. Top speed is stated at 208 mph (335 km/h). CarBuzz's full reveal coverage provides detailed context on the T.33 Spider's engineering decisions.
Suspension, Transmission, and Chassis
The T.33 Spider uses all-round double wishbone suspension with aluminium arms and high-pressure coil-over monotube dampers. The powertrain is semi-structural: the rear suspension mounts directly to the Xtrac six-speed manual gearbox casing, which weighs just 82 kg and is the lightest manual unit in any current supercar. A Salisbury-type limited-slip differential, carbon-ceramic brakes, and Michelin Pilot Sport 4S tyres complete the chassis specification. GMA applies its Inclined Axis Shear Mounting (IASM) system to the engine and transmission to dial in precisely the right amount of isolation for refinement while preserving sharp handling response. Autoevolution provides a comprehensive technical breakdown of the GMA.2 powerunit.
Aerodynamics: Murray's Ground-Effect Legacy
Gordon Murray's career spans Formula 1 cars including the Brabham BT46B fan car and the McLaren MP4/4. That experience shapes the T.33 Spider's aerodynamic philosophy directly. Murray and his team developed active rear downforce and clean underbody airflow without resorting to the aggressive wings, canards, and splitters that characterise most modern supercars. The result is a car that generates meaningful downforce at speed while remaining visually disciplined at standstill.
Photo: GMA
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