Carlos Sainz Jr left 'angry' by Toro Rosso-Renault F1 unreliability

The Spaniard failed to complete a lap of last Sunday's Interlagos race, after suffering an engine problem in the pitlane before the start.

The Renault power unit in the Spanish rookie's Toro Rosso shut down as he attempted a practice start on his way to the grid.

The car was towed back into the garage and the engine eventually fired up again, but it failed as Sainz attempted to join the race on the first lap.

Sainz also suffered electrical problems in final practice and qualifying, which meant he lost telemetry and the use of his clutch.

The suspicion is these problems caused damage to the engine that was not detected overnight on Saturday.

This latest retirement was Sainz's seventh of the season as the result of mechanical problems.

"I'm honestly very pissed off and angry with the situation, because I think we had a great opportunity to score points," Sainz said.

"It's the seventh time in the whole season. It means 50 per cent of the races not finishing.

"Obviously, it being my rookie year it's not what you want and it's not what you're here for.

"You're here to gain experience and to learn, so it's clearly not a good balance of retirements this season.

"You just hope that next year you have a clean season and that's it."

Sainz told reporters he was happy with his personal performances this season, despite the lack of results.

"When you are in your rookie season and you have so many failures but still manage to create an impression in the F1 paddock, it hasn't made me very sad at all," he added.

"I will go out of this year thinking what could have been without so many retirements, but happy with the overall performance."