Jacques Villeneuve has criticised his BAR team's performance as "unacceptable" after his third retirement in five races this season.
Villeneuve suffered engine failure on lap 13 of the Spanish Grand Prix when he had looked on course for a points finish.
"It's really hard to accept," Villeneuve said. "It's been like this for a few races this year now."
His frustration was heightened because he was already in the points and right behind team-mate Jenson Button, who had outqualified the Canadian by virtue of using a lighter fuel load.
"We had a heavier fuel load than Jenson so we end up looking stupid in qualifying. We had a better strategy but we could not use it," Villeneuve said.
Button, who qualified fifth, wasted a superb opportunity to score points for BAR when he collided with David Coulthard's McLaren while they were racing for position on lap 18.
He had to pit for repairs after the collision and trailed home ninth, behind the Jordan of Ralph Firman.
BAR have produced what most observers believe is their most competitive car ever, and yet Villeneuve and Button are 11th equal in the championship with three points.
Coulthard said he did not know what had happened with Button and would have to look at the video of the race.
But McLaren boss Ron Dennis blamed Button, saying the Englishman had produced a "badly judged overtaking manoeuvre".
Button, who finished ninth, refused to become embroiled in any row, declaring: "It was just one of those things, nothing more to say really. A racing incident."