Renault team boss Eric Boullier has admitted his growing frustration with his team's drop-off in performance.

Having taken 42 points in the first four races, in its last three outings the British outfit has accrued just 6 points, with Nick Heidfeld, in particular failing to convince.

Ahead of this weekend's Hungarian GP, which marks the beginning of the summer break, not to mention midway point of the season, Boullier admits that he's not happy, far from it.

"It wasn't the result we were looking for," he admitted. "We came to the Nurburgring with some developments to the car, which gave us higher hopes going into the weekend. Vitaly put in a determined drive, while lady luck did not favour Nick when he was working his way back up the field after falling back to 22nd position

"It was another point gained for us," he continued, "but really we were well below par, and it was not the weekend we expected it to be. It was not good enough.

"I've made no secret of the fact that I'm not satisfied with where we are, no one in the team is. We started the season well, but that feels like a while ago now and we have to face the facts, which are that we've been off the pace and we are trying hard to put that right.

"I've expected improvement from our car for a number of races now, and we are making improvement, but we have got to get our heads down and make bigger strides," he continued. "It's a competitive field out there, with Force India and Sauber also competing in higher positions, so we've got to raise our game starting in Hungary.

"We brought some developments to the car in Germany, which didn't produce nearly enough. So we are now all eyes forward to Hungary to ensure we have the opportunity to head on our summer breaks on a high."