The T400R and the T440R were originally known as the Tuscan R. They were to be the highest performance models produced by TVR and the ultimate version of this evolution was going to be known as the Typhon. The Typhon was to be fastest production TVR ever and together with its slightly smaller brothers lacked any electronic safety devices such ABS or any kind of traction control believing it to be safer without. Its power was originally planned to have stemmed from a 4200cc supercharged version of the stock 4000cc unit installed in the Tuscan, Sagaris, T350, Tamora and Cerbera Speed Six. The T400R and T440R respectively were in essence the platform for the Typhon and were required for homologation purposes – Although the T400R race cars were normally aspirated. The power was to be put down through either the Tuscan S manual gearbox, or a race-style true sequential gearbox with adjustable gear ratios. All the above names for this ultra high performance TVR effectively relate to the same vehicle but the names changed as the specifications and powers changed due to the length of time that the car was in development.

Unlike most TVRs which were relatively simple tubular steel spaceframes with fibre glass panels the Typhon and T400R and T440R had a combination of a steel spaceframe with full roll cage, combined with aluminium honeycomb sections, and a carbon fibre panels. The floor too was carbon fibre which allowed weight to be kept remarkably low compared to similar cars from Ferrari and Porsche, which were several hundred kilos heavier. The overall weight was around 1100kg couple with approximately 585 bhp (530bhp per tonne) in the supercharged version. This power to weight ratio was significantly greater than the Ferrari Enzo @ 484bhp per tonne. The whole chassis was designed from ground up using CAD/CAM software, a first for TVR who still tended to mainly use hand-draughted and clay sculpted design, reserving CAD for drivetrain design. These cars were also the first road going TVR to be supplied with adjustable dampers as standard, enabling customers to fine tune the car's handling characteristics.

However problems emerged during development, the range topping Typhon was due to be the fastest production TVR by large margins thanks to the engine producing 585bhp (400 and 440 bhp in standard normally aspirated trim). However the supercharged engine produced more power than required and well within safe tolerances for the block (initial specification for the engine was to be 500bhp) when installed in the car, it created a number of heat control issues, and after initial shake downs it was decided that it would not be suitable for production for safety reasons, and so the naturally aspirated Speed Six engines were the only engines available. The race-style sequential gearbox much like the engine never got to reach customer cars due to similar reasons it never got much beyond the development stage.

There are only a handful of these cars currently on the road and in different trims and specs. Once again TVR developed a monster capable of seeing off likes of Ferrari and Porcshe but like the Cerbera Speed 12 it never made it further than the prototypes and failed to become a full production car despite suggestions that it was available for order and numerous deposits taken from enthusiastic potential purchasers. It is extremely hard to know how many cars of this general type were produced for customers for the road.

Combined with multiple delays, the removal of the supercharged engine and specialist gearbox from the range caused almost all potential customers to cancel their deposits - as they were put down on the proviso that the car would have truly extreme world beating performance - resulting in only two of the 'neutered' cars officially being sold, as T4xx Typhon variants with the naturally aspirated engines and standard H-gate manual gearboxes. There were however a number produced for racing and indeed TVR were well represented at Le Mans with these cars on a number of occasions running the full 24 hours.