Tests were conducted before temperatures hit their peak See the vehicle

The JCB Dieselmax vehicle achieved the average speed during two runs on the Bonneville salt flats in Utah, USA.

Wednesday's record time beat a speed of 328.767mph (529km/h) the team had set just 24 hours earlier.

The Staffordshire-built vehicle was driven by Wing Cdr Andy Green from RAF Wittering in Cambs. He has said the car is capable of even higher speeds.

The previous diesel land speed record is 236mph (380km/h), set in August 1973.

A second record in 24 hours, which I don't believe has been done since the 1960s Wing Cdr Andy Green

The Dieselmax car is powered by two turbo-charged JCB engines built at the company's plant at Rocester.

Weather conditions helped toward the greater speed with cloudy skies meaning cooler salt temperatures to run on and favourable atmospheric conditions.

Wing Cdr Green completed a first run with an average speed of 365.779mph and returned at 335.695mph to set the latest record.

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

'Running too well'

"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."

Project director Tim Leverton had been confident the team would break the 350mph mark.

He said: "That was a bit dramatic. After the excellent first run, Andy couldn't get the front engine on boost.

"Both engines overheated yesterday so we made some changes to the cooling system and got it running too well.

"Our objective was to go 350mph so Andy actually went 0.092mph too fast, but we'll let him off."