Sealy, Texas - It may be unofficial but it's worth celebrating: Hennessey is building a limited run of just three World's Fastest Edition Venom GTs to commemorate its recent top speed run of 432.64km/h, set at NASA's Kennedy Space Centre in Cape Canaveral, Florida, on Valentine's Day, 14 February.

It's unofficial because the FIM defines a world speed record as the average of two runs in opposite directions, both completed within an hour, and a production car as one of at least 30 units - the Venom GT only did one run, and Hennessey has restricted production of the Venom GT to 29 cars, only 11 of which have already been delivered.

Nevertheless, any street-legal car that can hit 460km/h in a straight line is pretty impressive, and the Venom GT does hold one Guinness World Record: it's the quickest street-legal car from 0-300km/h, with an official time of just 13.63 seconds.

HOW'D THEY DO THAT?

The old-fashioned way, with a massive V8, squeezed to within an inch of its life, in the lightest possible body.

Like all Hennessey creations the Venom GT starts life as something else - in this case a 3.5-litre Lotus Exige.

Into the back of this dinky little aluminium and carbon-fibre coupe - so small that you don't so much get in as put it on - Hennessey shoehorns a 427 cubic inch (6995cc - that's a teaspoon short of seven litres, Cyril) General Motors LSX V8 crate engine with a cast-iron block, aluminium heads and dual precision ball-bearing turbochargers, mated to a British Ricardo six-speed manual transmission.

The whole car weighs just 1244kg and, as set up by Hennessey Performance Engineering, delivers 928kW at 6600 revs, backed by 1566Nm at 4400rpm, for a power-to-weight ratio of 746kW per ton.

PATRIOTIC COLOURS

The engine is redlined at 7200rpm and John Hennessey reckons that, given a long enough straight, the Venom GT will hit a theoretical maximum speed of 447km/h.

He said: "The Venom GT broke 270mph on the same runway where the Space Shuttle landed at the Kennedy Space Centre.

"We wanted to offer a special paint scheme that would incorporate the colours of the American flag - the same flag we flew on the Space Shuttle runway. Thus, our special livery package includes a body in white with red and blue stripes."

He makes no mention of any other features, so we must assume the World's Fastest Edition is mechanically unchanged. Nevertheless, even at $1.25 million (R13.4 million) each, $250 000 (R2.7 million) more than the standard Venom GT, the three examples to be built have already been sold.