The British team running the world's fastest diesel car have rebroken their own land speed record, nudging past the 350mph barrier with a speed of 350.092mph.

The JCB Dieselmax, driven by Wing Commander Andy Green, broke the 33-year-old record for diesel-powered vehicles on Tuesday with a speed of 328.767mph but eclipsed that shortly after daybreak in Utah yesterday.

Green completed a first run on the Bonneville Salt Flats with an average speed of 365.745mph and returned at 335.650mph to set the new record.

Weather conditions contributed to the greater speed, with a scattering of cloud cover meaning cooler salt temperatures to run on and favourable atmospheric pressures.

It is thought the car could be capable of much higher speeds, but it would need improved tyres to attain them.

Tyre technology for land speed racing has not changed much in the past 30 years, with companies reluctant to build fast tyres in case they are held responsible for accidents.

Louise Ann Noeth, an expert on record-breaking at Bonneville, said: "This car is capable of going faster than 400mph, I honestly believe that.

"But tyre technology hasn't changed for so long, and cars are running on old rubber.

"It would be great if Sir Anthony Bamford decided to fund a new tyre project to see how fast this thing can go, because then tyres would be available to other record-breakers."

After yesterday's success, Green said only technical issues had prevented him going even faster.

"Fantastic. A second record in 24 hours, which I don't believe has been done since the 1960s.

"But land speed records are all about unpredictability and I had some problems warming up the front engine, which meant I wasn't able to go as fast as I wanted on the second run.

"The car has still got loads to give. I throttled back on the second run and we haven't even used sixth gear yet, so the car can still go faster."

Dr Tim Leverton, project director, added: "Our objective was to go 350mph so Andy actually went 0.092mph too fast."

Sir Anthony, chairman of JCB, added: "I'm thrilled. It has been a great achievement.

"I had hoped, six or nine months ago, if we could go 100mph quicker than the previous record, that would be something, and we're well past. It's a reflection of our people and team, and of Andy. He is so cool and analytical. One could not hope for anyone better.