Under-fire BMW Sauber driver Pedro de la Rosa has admitted that he is finding life tough on his return to a full-time race role, but insists that things would be better if the team could attract some backing to help it develop the car.

Speaking to Swiss newspaper Blick, de la Rosa confessed that he has expected more than a single twelfth-place finish to show from the opening four races, but Sauber currently languishes among the three newcomers to F1 - Lotus, Virgin and HRT - having failed to score a point with either car. To make matters worse, de la Rosa concedes that the team's testing performances, however achieved, had been as misleading for those in Hinwil as they may have been elsewhere.

"It is frustrating," the Spaniard commented, "I knew that I should expect difficult times when I joined Sauber, but not that they would so difficult, especially after the tests in February."

While failures with its Ferrari engines - thought to be unconnected to those suffered by the Scuderia in 2010 - are high on de la Rosa's list of causes for the frustration, he also says that there are other areas of the C29 that need to be addressed, but bemoans the lack of finance to do so.

"Two engine failures are too much, but the back of the car is also too unstable, " he noted, "There is too much unrest in the rear but, without the necessary finances, the normal development of the car isn't possible. With each day, it gets harder to find for backers for 2010, but I remain optimistic as I have seen a team and a factory which gives me great confidence. We are making every effort and are certainly doing much better than our results show. I am sure that our hard work will pay off."

The Spaniard's upbeat attitude contrasts with rumours that he is already facing the axe after taking too long to re-adapt to a racing role after seven years primarily spent testing for McLaren. While rookie team-mate Kamui Kobayashi's result hardly put his in the shade - indeed the Japanese has four straight DNFs - de la Rosa is allegedly coming under pressure from the likes of Luca Filippi and Pastor Maldonado.

"Again, I'm not worried," he insisted, "I will have a few days holiday with the family in Majorca, and then return to Hinwil to see what is new on the car before the next race in Barcelona."