McLaren delays new car until Canada

McLaren boss Ron Dennis explained in Imola: "We will race it when we feel that it is as reliable as our existing car. That does not mean to say that we are not going to run it soon or that it is not going to be quicker. We know it will be quicker but to finish first, first you have to finish.

"With the rules as they are currently, you have got to have reliability or else you are history," he added. "The cost of unreliability in practice is severe and so we don't actually know when we'll race the MP4-18. I'd say no sooner than Canada, no later than Silverstone."

Kimi Raikkonen has a 100 percent podium finishing record this season with the updated MP4-17D, and currently has a 14-point lead over San Marino victor Michael Schumacher in the championship.

With the FIA having changed the scoring system this year, there is now just a two point differential between a victory and second place. Therefore, if Raikkonen regularly finished second to Schumacher, the five times champion would need to win every race up to and including Silverstone in July before overhauling the Finn.

Ferrari sporting director Jean Todt, meanwhile, confirmed that it was reliability issues that had also stopped Ferrari debuting the new F2003GA at Imola, but added that the car will be raced at Barcelona in a fortnight should its testing programme go to plan this week.