Although the team has tested extensively to try to understand what is wrong with the new R3 car, Irvine confessed: "We are really a little bit lost to be honest."

The R3 is so bad that the team have even considered reverting to last year's R2 car.

But that would not be the answer to the team's problems, even though it might be quicker in the short term.

"I am not happy with the R3. We know the R2 is the quicker car but potentially it is not," said the Nothern Irishman.

"There is a problem and we are trying to figure out what the problem is. We know the symptoms but we don't know what the disease is at the minute.

"We are eliminating things slowly but surely. That's all we can do because we don't know what the problem is.

"We changed so many things from last year to this, now we are going to have to go back to all those things to figure out which one is causing this problem that we have."

Testing sessions in Barcelona last month led to Jaguar officials insisting the difficulties had been addressed.

Australian boost

But the subsequent changes to the car failed to solve its problems and Irvine doubts whether anything will be resolved soon.

He said: "It didn't impact the problem whatsoever. So we are testing something else at Silverstone [next week] and it might be the answer, it might not."

Despite the dire underperformance of the R3 Irvine finished a surprise fourth place at the first of the season, the Australian Grand Prix, thanks to others dropping out.

But Irvine and team-mate Pedro de la Rosa are not expected to be competitive at the San Marino Grand Prix this weekend.