Speed matters, especially when it comes to the fastest cars in the world.
But what manufacturers claim their multi-million pound hypercars are capable of and what they have actually been proven to achieve are two very different things. That's why this list focuses on recorded times, not the 'theoretical' top speed figures. Unless it set a time in real life, it hasn't made the cut.
Like owning a watch that works on the moon, or a pen that can write at 200m under the sea, it's nice to know that, your car can perform miles-per-hour miracles - were you to find somewhere where it was safe and legal to do so.
With that in mind, here are the fastest production road cars by the numbers.
8. McLaren F1 - 386.4 km/h
Famously set by racing driver Andy Wallace at Volkswagen's Ehra-Lessien test track in March 1998, the monumental British hypercar carried the title of World's fastest production car for the best part of 15 years. However, that figure required the rev limiter to be raised to 8,300rpm - no production F1 has ever been recorded at more than 211mph, though unmodified, the 6.1-litre V12 should be capable of a still astonishing 221mph.
7. Koenigsegg CCR - 388 km/h
The car to knock the F1 off the top spot did do at Italy's Nardo Ring test track in February 2005. Koenigsegg's second-ever production model used a 4.7-litre twin-supercharged V8 to produce north of 800bhp and urge it on to beat McLaren by a single mile per hour. The record wouldn't stand for long, however; just two months later, Bugatti would take the crown in spectacular fashion.
6. Bugatti Veyron 16.4 - 569.4 km/h
At the time it was the most expensive and most powerful road car ever built, but VW Group bosses wanted the Bugatti Veyron to be officially the fastest car in the world as well. An 8.0-litre quad-turbocharged W16 engine produced 987bhp from the factory, with a seven-speed automatic gearbox sending power all four wheels. The car had to be put into its Top Speed Mode for the run, activated with a special key that retracts the rear spoiler, shuts the front air diffuser and lowers the ground clearance to just 6.5cm. The result? A record-breaking 253.8mph at VW's Ehra-Lessien test facility.
5. SSC Ultimate Aero TT - 412.15 km/h
SSC, then known as Shelby Supercars, produced the Ultimate Aero for seven years - not a long lifespan, but long enough to overtake Bugatti in the top speed stakes. In September 2007, the 1183bhp, twin-turbocharged V8 hypercar used a temporarily-closed two-lane stretch of public road near the Washington company's headquarters to set an average top speed of just over 256mph.
4. Bugatti Veyron Super Sport - 431 km/h
Not happy to have the record taken from them, and by an American car at that, Bugatti gave the Veyron a substantial overhaul in order to raise its top speed even further and have a new go at winning the title. The Veyron Super Sport was limited to just 30 cars, with each one seeing power output boosted to 1184bhp and aerodynamics overhauled to cope with the forces it would experience beyond 250mph. In July 2010, Bugatti test driver Pierre Henri Raphanel lapped the Ehra-Lessien oval at 267.856mph.
3. Hennessey Venom GT - 435.2 km/h
American tuning house Hennessey Performance Engineering is no stranger to speed, having previously taken its Dodge Viper-based Venom beyond 215mph. It was the Venom GT, which used a Lotus Exige as its foundation, that would go on to steal the record from Bugatti - though not without controversy. In February 2014, on the 3.2-mile space shuttle landing runway at Florida's Kennedy Space Centre, it recorded a one-way speed of 270.49mph. However, NASA wouldn't let Hennessey attempt an opposite direction run, and so didn't qualify for an official Guinness World Record.
2. Koenigsegg Agera RS - 447.1 km/h
When it used a customer-owned Agera RS to earn the outright world record top speed in 2017, Koenigsegg also took the record for the highest speed ever recorded on a public road. Mercedes had held that particular crown since 1938 when a highly modified W125 Grand Prix car managed 268mph on a closed stretch of Autobahn. As an indication of 80 years of progress, the Agera RS was entirely standard, with the company's optional 1MW engine package producing a colossal 1360bhp.
1. Bugatti Chiron Super Sport 300+ - 490.4 km/h
The undisputed top speed champion is once again a Bugatti. Again limited to 30 customer cars, like the Veyron Super Sport, this purpose-built speed machine was taken to 304.773mph by British sportscar veteran Andy Wallace at the VW Group's Ehra-Lessien test track. Appropriately nicknamed Thor (because it brings the thunder), the Chiron's quad-turbocharged W16 engine produced 1578bhp in record-setting guise. It was given a new gearbox with longer ratios, and front and rear bumpers that were optimised for high speed runs.
Who will be next to break the record? The contenders
With Bugatti having promised to bow out of setting production car speed records, there are several potential successors to its crown.
Hennessey Venom F5 - over 300mph (claimed)
Hennessey says its Venom F5 carries on where the Venom GT left off, with a 6.6-litre twin-turbocharged V8 producing 1817bhp and 1193lb ft of torque. It should be capable of 0-60mph in under two seconds, and has a theoretical top speed of over 300mph.
SSC Tuatara - over 300mph (claimed)
SSC will only build 100 Tuatara hypercars, with each expected to cost upwards of $1.3 million, although customers have been waiting the best part of a decade for the project to see completion. Originally planned with a 6.9-litre twin-turbocharged V8, the production car is set to use a 5.9-litre block with a higher redline. On E85 fuel, it should produce 1750bhp and be capable of more than 300mph in a straight line.