The T.33 uses a version of the Cosworth 4.0-liter V-12 engine that powers the T.50. Here dubbed GMA.2, it carries modified heads, new cams, new intake and exhaust, and reworked valve timing. The aim was to make the engine better suited for daily use, with a nice broad torque curve and a lower redline. These things are relative, of course—that “lower” redline is now 11,100 rpm; the GMA.2 has a 14:1 compression ratio, makes 607 hp at 10,500 rpm and 333 lb-ft of torque at 9000 rpm, and delivers 75 percent of its peak torque as low as 2500 rpm and at least 90 percent from 4500 to 10,500. It’s still a clean-sheet, naturally aspirated Cosworth V-12, after all.
Murray is especially proud of the intake design. “I’ve always wanted to do a road car where the airbox is attached directly to the engine and moves independently of the body,” he says. On the T.33, the air intake pokes through the glass engine cover, similar to the track-only GMA T.50S. “When I told [Cosworth] 33 needed to have an airbox like that, there was a lot of silence, pregnant pauses and sucking of teeth,” Murray says, admitting that the request was, in his word, “wacky.” The four throttle bodies sit inside the ram-air box, feeding a separate plenum for each cylinder bank, a setup Murray credits for the GMA.2’s impressive torque curve.
The transverse Xtrac six-speed manual transaxle uses the same casing found in the T.50, with different internals and unique ratios. Unlike the T.50, this model will offer the option of a paddle-shift six-speed sequential automatic, similar to a unit Xtrac builds for touring car racing. Murray claims this transmission offers the world’s fastest gear-change.
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The T.33’s chassis is entirely unique, built according to Murray’s “iStream Superlight” principles. An aluminum tube-frame spans nearly the full length of the car, with bonded carbon-fiber panels making up the passenger compartment and engine bay. Most carbon-fiber supercars use a central carbon monocoque with aluminum or steel front and rear subframes bolted on. “The problem with that is … every time you bolt something, it’s quite complicated and heavy, and it is flexible,” Murray says. In the T.33, the continuous aluminum tube frame has no joints, eliminating this potential for flex, and the bonded carbon fiber adds strength and rigidity where it’s needed.
This chassis, with its metal-and-carbon-fiber construction, ends up about 200 pounds heavier than the T.50’s full-carbon-fiber monocoque, but it will form the basis of multiple future GMA models, including hybrids and EVs. And the T.33 is still an incredibly lightweight vehicle at 2400 pounds—less than a McLaren F1, and as Murray points out, with a power-to-weight ratio that approaches the LaFerrari.
The suspension design is pure and simple sports car: Double wishbones all around, the rears mounted directly to the transmission casing, with coilover springs and passive dampers. There are no electronic suspension modes, no adaptive valving, not even an anti-roll bar at the rear. As he did with the T.50, Murray took inspiration from his daily driver, a new-generation Alpine A110, a vehicle he says strikes the balance between handling and ride comfort better than anything currently on the market. (Murray loves using mass-production sports cars for his ride-and-handling benchmarks: He took inspiration from the first-generation Acura NSX while developing the McLaren F1.) The GMA team took apart Murray’s A110 to see if Alpine had used any chassis or suspension tricks to achieve this delicate balance. They found none.
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The biggest change from T.50 to T.33 is at the rear. The T.50 uses a zany aerodynamic setup with an electric fan sticking out of the rear bodywork that can generate downforce or reduce drag depending on drive mode. The T.33 uses a much simpler setup. There’s a deployable spoiler at the rear, but around two-thirds of the car’s downforce is generated by large diffusers behind the front wheels, which allowed GMA to avoid adding ungainly splitters or dive planes. The design came about almost by accident: While experimenting with virtual setups for the T.50’s fan-based aero system, a GMA engineer came up with a design that generated downforce even when the fan was switched off. That layout was adapted for the T.33.
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The T.33 is priced at £1.37 million before taxes, which is about $1.85 million at today's exchange rates. No doubt, that’s an awful lot of money—though it’s nearly $800,000 less than a T.50, and around $150,000 less than the 200-mile Carrera GT that just sold on Bring a Trailer.
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