The Nemesis, a heavily-modified Lotus Exige which was originally bought off eBay, clocked an average speed of 244km/h. The old record was 220km/h.
The car was designed and built by a team of British motorsport engineers in Norfolk, and driven by estate agent Nick Ponting, 21, from Gloucestershire.
Ponting said: "It was brilliant. The car felt really good. The conditions were perfect.
"We've smashed the record and then gone and done a second run and done it again.
"The acceleration is phenomenal. It gets to the top speed very quickly," the BBC quoted Ponting as saying.
The car runs on green electricity which has been generated by wind turbines.
The record still needs to be ratified by the Motor Sports Association before the record can be officially declared, the report said.