Jarno Trulli says his Toyota team have had too many problems with their new car to be able to judge how competitive it is.
The Italian driver is frustrated by the reliability problems the Japanese squad have endured during winter testing with the new TF107, and he admits he has not completed enough mileage to be able to judge the potential of the car.
"I have not done many laps, so I cannot judge the car yet, I hope in the next test we will find out," Trulli told autosport.com during testing at Jerez. "We had some problems in Jerez and also in Valencia, it's still early days.
"We have had too many problems around the car to really judge it. I have not been able to change the set up at all. I had problems in Valencia and also at Jerez. We are still running with the same set-up as we started," he added.
"The initial impression of the car was okay. There is nothing wrong in a major way, but we are struggling a lot more on the rear end. We have some work to do."
Despite the problems, Trulli says the TF107 has initially felt good, and he is looking forward to testing new developments which should make the car more competitive ahead of the first race.
"The feeling is that is good, although I keep saying it is too early," he said. "This car is not the car to race in Melbourne, a lot of updates are coming, for other teams too. There will be lots of new parts which will be introduced in the next few weeks.
"Everyone is trying to test and improve the car. I hope I will have better test in Barcelona (next week)."
Toyota are targeting their maiden Formula One victory this year following a disappointing 2006, where they finished in sixth place with 35 points and just one podium.