Webber laments 'unbelievable' retirement

The Australian was running in a strong fifth place when his Red Bull Racing car stopped on lap 14 with transmission failure.

The retirement, compounded with teammate David Coulthard's failure to get in the points, meant that the Milton Keynes outfit could not overhaul Williams for the fourth spot in the Constructors' Championship.

"I had a good start and our pace was not too bad," explained Webber. "I hoped to get some good points, but then something failed on the car. It's pretty unbelievable really.

"The guys saw a disconnect between the engine and the gearbox, which is another new issue by the looks of it, but it's early days and we need to investigate it further to see exactly what happened.

"We were on for some good points, so it's a real shame."

Coulthard, who classified ninth at Interlagos, reckoned his package lacked pace compared to his rivals and suffered from an ill-handling car for the last part of the race after a collision with Williams debutant Kazuki Nakajima.

"I thought we might get into the points today, but unfortunately I didn't have enough pace relative to the cars in front," said the Scot.

"I came together with Nakijama towards the end of the race, which knocked my front suspension out and the car was moving strangely around left-handers for the last ten laps. We just weren't quick enough today.

"I would like to thank every member of the team, both race and test and everyone based at the factory, for all their efforts this year.

"As difficult as this season was, it's only going to get more difficult as we move forwards - but I'm up for the challenge and I'm sure they are too."