Since July 13, Alan and the team have broken FIA class world records three times over, ending Thursday with an average speed of 397.360kph (246.908mph) over two runs of the Bonneville flying mile.

At the same time, van der Merwe set a new class record for the flying kilometer, with an average speed of 397.481kph (246.983mph).

Both speeds again set a new mark for the fastest officially measured speed by a Formula One car, pending official ratification by the FIA.

The atmosphere was full of anticipation on the final day of high-speed running, as the project team arrived on the salt flats in the hope the records could be raised. The team was ready to go as dawn broke, having carried out a gearbox change late into the previous night. Alan rolled onto the course at 6:40 a.m. local time and consistently recorded times above 390kph all morning until his record-breaking run at 9:02 a.m.

Unfortunately the team lost a driveshaft late in the morning that damaged the differential and were forced to draw a line. Throughout the challenge, the Honda 3-liter V10 engine provided unabated power and reliability.

The intermediate tires that Michelin supplied performed exceptionally well during the high-speed running on the flats.

Michelin provided advice on set-up changes and all of the attempts were made with Michelin F1 tires.

"I think in general the feeling is satisfaction with what we achieved. It would have been nice to have a round number for the record and we are only two and half kilometers off that. In fact, we know we did everything possible to the car; we timed it exactly right today with the weather and we’re pretty sure we couldn’t have got more out of it, possibly another kilometer an hour but we would have needed good weather to do that," Merwe said.

"I’m really happy and slightly relieved as well, because it has been really stressful, every day, and we now know we have had the best day possible to run the car. And also the fact that the team did really well – the first thing to let go was the car. Altogether its been great to set the record and very rewarding to reach 400kph, its been a great week," van der Merwe added.

Mike Cook, president of the Southern California Timing Association (SCTA) and veteran of several land speed record attempts at Bonneville, was equally as pleased that the team had stayed on to push its own records even higher.

"First of all, I want to say we really feel the team came out and worked very, very hard right down the side—they truly are Bonneville racers now," Cook said.

"They accomplished a 246.980 average for the mile, which means they have increased their speed again, and they got a 397.481 so today was a success. They didn’t get a 400 record but they got their 400 one-way run, so maybe it’ll enthuse them to come back! Anyway, they got a record and they’re going home with a record," Cook added.