Interceptor Insanity: This Mad Jensen's Button Gives It 3000hp

Duncan Davis still can't believe his good fortune. He may not own the super-rare Jensen Interceptor beside which he is standing here, but he's the chap who drives it.

"Its owner is my best friend," he explains, "but he lives abroad so I look after it and get to drive it and his other cars to events such as today's Goodwood Breakfast Club meet." Duncan's smile is as wide as the Jensen's grille, and it quickly becomes apparent why.

"This car is a one-off: the only lightweight Interceptor Jensen made," he says. "It's a manual, too – one of just 24 – and has no power steering. The guy who originally purchased it new in 1964 said he wanted a lightweight car to take on the track.

Jensen told him it didn't make racing cars but agreed to remove most of the comfort features, including the soundproofing, and fitted a glassfibre bonnet. It also uprated the suspension and replaced the regular Chrysler 6.3-litre V8 engine with the more powerful 440 [7.2-litre] Magnum Chrysler engine.

By the way, the GTR badge on the tailgate is an afterthought and was not Jensen's idea." The Interceptor's present owner bought the vehicle in 1981, but Duncan won't reveal his name. He does, however, reveal a few tantalising facts about him.

"He's a very bright man and used to work for the secret service – or was it the government?" says Duncan. "Whatever, I believe that between 1981 and 1995 this Interceptor was used by MI5 and driven around London. Incredibly, the last three digits of its engine number are 007!" 

Meanwhile, not content with the engine's regular power, the car's mysterious owner decided to uprate it. "He designed the engine in his head and in 2012 told his engineer what he wanted," explains Duncan. "The chap said it wouldn't work. My friend told him to just do it. He paid him, the engineer did it and it works!" 

What was done? First, the engine was fitted with Nascar race internals and bored and stroked to 8.1 litres. With advanced ignition, a tuned exhaust and ram air, its total power output is 750hp. Next, water methanol injection, a system that boosts it to 825hp, was added as an option. Finally, a nitrous oxide system was installed.

It delivers three 450hp shots of the stuff, the first at 70mph, the second at 120mph and the third at 170mph. With what Duncan calls the assistance of "true ram-air forced induction", the Interceptor's maximum power output is 3000hp at 200mph.

Naturally, this drag mode is for straight-line runs only.  To protect the glassfibre bonnet, its underside is lined with gold foil. Or is the foil a nod to the engine's '007' and that arch-villain, Goldfinger? Duncan won't be drawn. Whatever, it and the car's oversized air cleaner housing always draw a crowd.

Duncan says he is approached by many festivals and organisers wanting to run the car at events and hillclimbs, but its owner always declines. "The car is too rare and valuable to risk it being crashed," he says.

"However, my friend doesn't like to say no and has agreed to commission another Interceptor, also a lightweight but this time an automatic and powered by an engine producing 2000hp. It's still two or three years away, but it will happen."