Over two directions in an 11-mile stretch of Highway 160 between Las Vegas and Pahrump in Nevada, helpfully closed by the local authorities.
On the first, Koenigsegg test driver Niklas Lilja hit 271.2 miles per hour, fast enough to best the unofficial one-way record of 270.39 miles per hour set by the Hennessey Venom GT in 2014. Last month, the Agera RS pipped the Bugatti Chiron by performing the world's fastest ever zero to 400km/h to zero acceleration and braking run for a production auto, performing that feat in 36.44 seconds.
Like many people, we were wondering just what kind of peak speed was achieved during Koenigsegg's record-breaking run with an Agera RS.More news: India hails women's hockey team for Asia Cup win after 13 years
The Bugatti Chiron is its closest rival with a top speed of 261mph, although Bugatti claims it has the potential to hit 310mph in the future.
Using a customer vehicle, the Swedish manufacturer confirmed on Twitter that it had received permission to close the road for two days, but needed just three runs - one sighting run, then a full-chat effort in each direction - to break the old record. Part of that speed verification is in video form below.
The test was then carried out using Michelin Pilot Sport Cup 2 tyres which are the tyres the Koenigsegg is sold with and are authorised for use on the road. It recently announced that the successor to the Venom GT, the 1600-bhp Venom F5, could break the 300-mph limit. This is not the first time that Koenigsegg broke a world record held by Bugatti, as it happened just last month. Recall hypercar Koenigsegg has a 5.0-liter V8 twin-turbo power 1360 HP (1 MW).