McLaren may debut MP4-18 at British GP

The team was scheduled to race it for the first time in the European Grand Prix at the Nurburgring, but the team's technical director Adrian Newey has hinted that the car is not ready after it failed to complete a race distance in last week's private Barcelona test.

"Pace and reliability have to be the deciding factors," he said. "We have said since we released the car that the Nurburgring was the earliest we thought we could race it. I think we will probably take the prudent view that it is a little bit early. But we haven't made that decision yet.

"The problem is that after the Nurburgring you have Magny-Cours the week after, which puts the debut back to Silverstone."

A final decision is expected to be made in the week after the Canadian Grand Prix and Newey has suggested that it may be that the team gambles on running just one new car initially, as Ferrari did with the F2002 in last year's Brazilian GP.

"You only split the team old car/new car if you don't have enough parts to support two new cars," said Newey, "or if you felt the new car had more performance and were concerned about reliability."