With four weeks to go before the first race of the season, and his Toyota bosses in Japan demanding at least one trip to the podium this year, Jarno Trulli has revealed that he is unhappy with the handling of the TF105.

"The car seems quick and competitive, he told Gazzetta dello Sport, "but not over the distance. The problem is excessive rear tyre wear, and we have just three weeks left and we hope to resolve it.

"It's definitely not due to the weight distribution," he continued. "But we still haven't worked out whether it is an aerodynamic problem or mechanical. After three laps the car becomes more difficult to drive, and in that it reminds me of my old Jordan. It's a shame because the car is easy to handle and the problems of engine reliability have been resolved."

His admission will come as a shock to the Cologne based team and to technical director Mike Gascoyne, however it possibly explains why some of the test times - particularly Ralf Schumacher's - have been disappointing.

The Italian's revelation comes on the back of similar admissions from BAR and Sauber, with the British team claiming that its 007 lacks aerodynamic performance, in addition to suffering an alarming number of engine failures. Indeed, in testing, the Honda power-plant has yet to pass the 'magical' 1300 km barrier - the equivalent of two race weekends - which is the expectancy for 2005, when the two race rule is introduced.

While Sauber has admitted a 'design flaw' which means that its C24 is not as fast as expected, this is in spite of the fact that the 2005 is the first product of the Swiss outfit's much heralded state-of-the-art wind tunnel. On the other hand, Sauber claims that reliability is not an issue.