Bio-diesel supercar: The green mean speed machine

Supercars are all about statistics, from the obscene asking price through to the terrifying top speed and the untenable miles per gallon. They give the greenies and the pinko car-hating lobby loads of reasons to be even less cheerful than normal.

In theory then they should really hate the Trident Iceni R. It has a 6.6-litre twin-turbo V8 engine producing 450bhp. It will do 230mph and get to 60mph in less than four seconds. But, and this is the kicker, it runs on locally produced biodiesel, and at a constant 56mph the Iceni will return a Smart car-beating 70mpg.

So where has the Iceni come from? Well, if you know your regional history, you'll know that the Iceni were Boudicca's gang who hung out in the Norfolk hood back in 60AD. Also Trident Cars was a manufacturer of sports cars in Suffolk. So, unsurprisingly, Trident Iceni R is being handbuilt on an industrial estate just off the A47 in Norfolk by Trident Performance Vehicles.

There have been several false starts in its evolution, the last back in 2000 at the Motor Show, when deposits were taken but full production never became a reality. Changes in management, restructuring and refinancing have brought the manufacturers to the point where they not only have a racing version which competes against petrol-powered supercars, but are also building cars for customers.

So what's the secret of the Iceni R's remarkable stats? "Torque multiplication," says Phil Bevan, the chief designer. "Diesels operate more efficiently within the right rev range and fewer revolutions mean less friction. So a 2.5-litre diesel engine hammering down the M4 at 4,200rpm is not very efficient when with modification it could be doing it at 1,000rpm. Diesel engines are torque rich, but brake-horse power poor."

Probably with the Bugatti Veyron's 1,000bhp-plus in mind, Bevan insists he is not interested in bhp. "It's a myth," he says. "The most important thing is optimising the efficiency of an engine. In Formula One, the optimum rev point is 18,000rpm, which means that all gear changes occur at this figure. With the Iceni R it is 3,500rpm, and our computer model shows that at 56mph the engine generates 402rpm and that works out at 71.5mpg."

To start with, Trident modifies the General Motors diesel so that it will be able to take maximum revs all day long when required. At the back of the Iceni is an eight-speed automatic gearbox designed by Bevan.

"We're using the cogs in the gearbox in a different way," he says. "The gear-change severity is based on a cruise mode which means there are seamless changes. When we race there are manual paddle shifts, but on a day-to-day basis that would be tiring so it's better to be fully automatic."

There are few details about his clever patented device, which is built in America because no one in the UK would back it. But why bother to go racing? "The race car was the only way to show to customers that we can build cars," he says. "First of all we have perfect 50-50 weight distribution with the front engine set well back."

The racing engine produces 450bhp and 800lbs of torque - virtually three times those of the Ferraris they compete against - and is geared to reach 230mph. Road cars will only do 170mph, but getting to 60mph takes the same time, under four seconds.

At Silverstone, though, Bevan noticed the difference. "On the main straight the Ferrari will be doing 8,000 revs and it will scream past," he says. "When the Iceni goes past it is nearer to 3,000, and although it is doing 140mph it sounds like it is purring along at 50mph.

"We also built a diesel race car because it can be done at less cost and wastefulness. A GT race lasts two hours, which uses 100 litres of petrol in the first 45 minutes, and when there is a driver change another 100 litres are added. With our car we race with 45 litres and never need to fill up."

So while a Ferrari 360 does 8-9mpg during a race, the Iceni manages a rather more impressive 48mpg. "We can have as much fun as someone with a Porsche GT3 at 18 per cent of the cost, so environmentalists can't complain, especially as there are no carbon emissions," adds Bevan.

It is easy to live with mpg figures like that, but supercars have a reputation for costing a fortune to run and being less than practical. Bevan explains that the General Motors diesel engine has its first service at 100,000 miles and the gearbox is sealed for life. "The stainless steel chassis has a 100-year guarantee, while the Kevlar carbon fibre body means that it's a car that you can hand down to your grandchildren," he says.

Not only is there a decent-sized boot, with room for more than a couple of soft overnight bags, but also you won't have to stop every 20 minutes, as you do when the Bugatti is topping 200mph. "You can get from Norwich to Monte Carlo and back, as the Iceni will do 1,000 miles on a tankful," adds Bevan. "What we wanted to do was bring back the true GT car."

At just ?60,000, the asking price will be considerably less than six-figure Ferraris and Lamborghinis. And although in the past, good-value British supercars like TVRs were light on safety features like ABS brakes and even power-steering, the Iceni comes with everything as standard, including traction control, satellite navigation and rear-view cameras. Trident even makes its own 20in alloy wheels. All the buyer does is choose the colour and sound system.

But every buyer has the car set up to handle just as they want it because the forged aluminium suspension geometry and settings can be changed to suit, as are the the seat, pedal box and steering. So who is going to buy this socially responsible supercar?

"This is a niche market," admits Bevan. "They will be farmers, haulage contractors or company owners who are already heavy diesel users. People who don't want the frenzy of a supercar and will use it as a business tool." Indeed, one customer who just happens to be a farmer is actually going to make his own fuel.

Here it is then, the supercar you don't have to apologise for buying or driving. It's fast, it's frugal and it doesn't cost much to run; it's the answer to every objection the anti-car lobby has ever raised.

All Trident has to do is build this Iceni to a consistently high standard, remain financially sound, not grow too fast and it will have to beat off customers with a cattle prod. I sincerely hope it gets it right because singlehandedly the company could make British GT cars sexy again.

See www.trident-vehicles.co.uk or call 01328 700022