Theon Design Reveals Its 419bhp Air-Cooled Porsche 911 With Commissions From £435,000

• Theon Design starts a Coupe commission at £435,000, before the donor car, shipping and local taxes, and each car takes 18 months to build.
• The latest Coupe carries a 4.0-litre air-cooled flat-six with 419bhp and 322 lb-ft, in a car Theon Design puts at 1,150kg and about 4.0 seconds to 60mph.
• A 500bhp-plus Theon R is in build for its first customer, and a new online configurator now covers the Coupe, Targa and R.

Eighteen Months and £435,000 Buy a 964 With a Carbon Body and a Town Mode

Theon Design builds air-cooled Porsche 911s to order at its Deddington workshop in Oxfordshire, and a Coupe commission starts at £435,000. That figure leaves out the donor car, shipping and local taxes. Theon Design says every car is a one-off made with its customer and needs 18 months in the workshop.

The latest finished example is a Porsche 911 (964) in Oak Green Neo Metallic, developed over those 18 months with a UK client and revealed on 12 November 2026 as the company marks 10 years in business. Theon Design quotes 419bhp and 322 lb-ft from its 4.0-litre flat-six, a mass of 1,150kg and a 0 to 60mph time of about 4.0 seconds. Those are the maker’s figures, not independent test results.

Buyers can start in the company’s new online configurator, which lists colours, materials and specifications for Coupe, Targa and R commissions. Theon Design says the configurator only starts the process and that close work between client and team stays central to every car.

What the £435,000 Covers and What It Leaves Out

The donor is either the customer’s own 964 or a car Theon Design helps to find. Whatever the donor costs goes on top of £435,000, so the starting price sets the minimum spend. For the latest car, the team stripped the donor to its bare shell and then worked through the structure, the mechanical systems and the smallest functional details. Theon Design describes that donor as a 35-year-old car.

Adam Hawley, Co-Founder of Theon Design, a former senior designer for BMW, Jaguar, Land Rover and Lotus, explains the approach after a decade of commissions:

“The air-cooled Porsche 911 has legendary integrity of design and engineering. The car’s proportions, mechanical character and unfiltered connection with the driver are fundamental to its enduring appeal. Our ambition has always been to elevate those qualities while respecting the principles behind the original design. That requires experience and discipline – knowing what to evolve and, just as importantly, what to preserve.”

“Ten years on, that conviction remains central to everything we do. We don’t measure progress by the changes we introduce, but by how naturally each enhancement belongs to the car. The result must feel cohesive, fully in keeping with Porsche’s engineering ethos and unmistakably true to the spirit of the original 911, as it subtly evolves into a distinctly personal character shaped by its owner.”

Hawley founded the company in 2016 with Lucinda Argy, a business and marketing specialist. Readers who want to see another reimagined air-cooled 911 can browse the site’s photo gallery of the Singer Carrera Coupe.

Classic Car MOT and Tax Exemptions Look Out of Reach for a 35-Year-Old Donor

A 35-year-old donor car sits outside the rules that let classic owners skip the MOT and vehicle tax. GOV.UK lets a vehicle skip the annual MOT on two conditions. Its build or first registration date must be more than 40 years back, and it must have no substantial changes, with a replaced chassis, body, axles or engine given as the examples. A car that is 35 years old falls five years short of the first condition, and an upgraded powertrain plus carbon-fibre body panels point the same way on the second.

The vehicle tax exemption works on build date. From 1 April 2026, a vehicle built before 1 January 1986 can stop paying vehicle tax, and a vehicle with an unknown build date qualifies if it was registered before 8 January 1986. A car 35 years old was built after that date. Anyone planning a commission should budget for the annual MOT and for road tax on older cars, where the government has already turned down calls for a cut.

This reading rests on the age and the work Theon Design describes, not on a DVLA ruling about any of its cars. Owners of a rebuilt classic of their own can read about the the registration rules for reconstructed classic cars that DVLA eased this year.

A Flat-Six With a Town Mode, and 300kg Out of the Body

The rear wheels take the drive through a five-speed G50 manual. Theon Design also offers a closely stacked six-speed in 993 RS specification, which it calls the more sporting option. The company says the five-speed gives this car an eager feel on rewarding roads and a relaxed one over longer distances. Drive-by-wire throttle and a choice of engine maps, one of them a town mode, let the driver change the engine’s response for different conditions. Porsche 993 RS brake discs and calipers handle the stopping, with the callipers colour-coded to the champagne PORSCHE script.

On the maker’s figures, 419bhp in a 1,150kg car works out at about 364bhp per tonne. The body explains much of that. The exterior panels, bumpers, lower sills and interior trim panels are F1-grade carbon fibre from a composites supplier that works only for Theon Design, and the company says the carbon saves about 300kg.

Two hidden changes add to the saving. A MIL-specification wiring loom takes the place of the bulkier original and saves about 25kg. An all-electric heating and air-conditioning system takes the place of the heat exchangers, saves about 2 to 3kg and warms the cabin almost at once, so a cold winter morning no longer means waiting for the engine to come up to temperature.

Dampers and Tyres Set for Rough Roads

Theon Design fitted TracTive semi-active dampers, spring rates set for the car and a steering package tuned for this client. The 17-inch wheels carry Michelin Pilot Sport tyres, and their taller sidewalls add compliance on pock-marked roads, as the company describes the choice. Inside, the cabin carries Beechwood semi-aniline and nubuck leather trim and Recaro CS seats, and the window switches are now milled from aluminium.

Hawley says the client shaped those choices:

“As with every commission Theon Design undertakes, this project began by listening to what the client wanted – not just how they wanted their car to look, but how they wanted it to feel. That informed every aspect of the development programme, from the engine, transmission, and brake package to spring rates, damper calibration, and steering response.”

“Throughout the eighteen-month development period, we spoke regularly with the client, involving them in all the decisions that would affect the car’s character. From the first conversation to the final sign-off drive, collaboration is key and ensures that the ownership experience is every bit as personal and rewarding as the design.”

The Theon R Takes Aim at 500bhp

The first customer Theon R is now in build. The R pairs a high-revving 4.0-litre flat-six making more than 500bhp with motorsport-derived chassis technology and F1-grade carbon fibre for every body panel and throughout the cabin. The company targets a mass of less than 1,000kg, which would put the R above 500bhp per tonne on its own figures. The £435,000 starting figure applies to Coupes.

For North American buyers, Theon Design has added a concierge service through Humble House, with on-the-ground support alongside the direct line to the Oxfordshire workshop.

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Reviewed by Preetam Gadekar