Rubens Barrichello has admitted he would like more performance from the Cosworth engine.
According to Brazil’s Globo, the Williams driver is expecting a step forward from the returning British supplier in Turkey later this month.
"We have some problems with the engine power," Barrichello admitted. "We have not extracted the full potential of the car so far. We hope that Cosworth improve the power in the European season, but it’s still early.
"They’ve already changed a few things. There should be good developments for Istanbul and I’m already looking forward to that race," he said.