The Hennessey Venom GT is the fastest road car in the world, setting a mark of 270.49mph early in 2014. It beat the previous title holder, the Bugatti Veyron Super Sport, by just 0.63mph - but the record won't be officially recorded.
Hennessey took its car to the Kennedy Space Center in Florida, USA to run the car on NASA's 3.2-mile Space Shuttle landing runway.
The official Guinness World Record requires two runs in opposite directions to work out an average speed - meaning tailwinds are taken into account - and since the Venom GT wasn't able to do this on that runway, the record books remain unchanged - the Bugatti is still technically the champion.
“The Venom GT attained a maximum speed of 270.49 mph as measured by our VBOX 3i GPS system,” said Racelogic engineer Joe Lachovsky - independently verifying the speed that was reached.
The Venom GT also holds the speed records for world’s fastest car from 0-300 km/h (13.63 seconds) and 0-200 mph (14.51 seconds). That's thanks to a low weight (1,244kg) and a high power output (1,244bhp) from its 7.0-litre twin-turbo V8 engine.
The Bugatti Veyron Super Sport, which reached 269.86mph in 2010, is technically still the fastest road car - and it's the effortless way that the car reaches this top speed that really impresses. Thirty models were produced initially and five of those had the top speed limiter removed to allow the incredible top speed to be reached - and to ensure the car's place in the record books for production cars.
The original Bugatti Veyron without the Super Sport tweaks set a speed of 253.81mph in 2005 - it's a previous winner of the title, and undoubtedly an incredibly fast road car. Its 8.0-litre W16 engine has four turbochargers and produces 987bhp - 0-62mph takes just 2.5 seconds.
The McLaren F1 was a sensation in the 1990s, setting an incredible speed record that stood for more than 10 years. In fact, it still holds the record for world's fastest naturally aspirated road car, setting a speed of 240mph way back in 1993.
Notably, it features a central driver's seat and two passenger seats either side - an unusual set-up for a hypercar like this. It uses a 6.1-litre V12 with 627bhp - quite a bit less than the Veyron, but it does weigh less than the Bugatti too.
The early nineties were an incredible time for hypercar fans, with the top speed war in full swing between the McLaren F1, Ferrari F40 and Porsche 959. The Porsche was the first to hold the record of the three, but the F40 soon trumped the Porsche's 195mph with its groundbreaking 202.6mph - the first road car to go faster than 200mph.
The Lamborghini Miura was the fastest road car in the world at the time of its launch in 1966, able to reach a top speed over 170mph. Before that, the Aston Martin DB4 and Mercedes 300SL held the record, as well as the Jaguar XK120.
One speed record that will likely never be broken is that of the Mercedes-Benz W125 Rekordwagen - a converted 'silver arrows' grand prix car with an ultra-aerodynamic body and a 5.6-litre V12 with around 725bhp. In 1938 the car drove on a public road to a speed of 268mph - with today's congested roads there's no way this will ever be repeated.
While the Bugatti Veyron and Hennessey Venom GT fight over whose attempt will go down in the record books, the Koenigsegg One:1 looks set to blast in with a record of its own.
Even if it can't match the ultimate speed record, the One:1 will become the world's most powerful road car with 1,322bhp - 22bhp more than the current champion, the 1,300bhp SCC Ultimate Aero.
Find out about the current crop of 200mph heroes in or top 10 fastest cars on sale...