David Coulthard may have to wait until his home British Grand Prix next month before he can give the new McLaren its race debut.
"I think you won't see it before Silverstone now," said the Scot at the Canadian Grand Prix, mid-point in the Formula One championship.
McLaren have been testing the new MP4-18 in Spain, with Finland's Kimi Raikkonen crashing heavily last week, and were targeting a debut at the European Grand Prix at the Nuerburgring on June 29.
Further tests in Spain next week are likely to decide whether that is feasible but technical director Adrian Newey has suggested the Nuerburgring could be too early for reliability issues to be resolved.
France follows on the weekend immediately after the Nuerburgring and the logistical problems posed make Silverstone, round 11 on July 20, the next workable date.
Coulthard felt the MP4-18 would be worth the wait.
He said: "Obviously over the years you get a feel for cars. There is no point saying it is going to blow everyone's doors off or anything like that because it will be what it will be on a racing weekend, that is the important part. But I think we can be optimistic."
Coulthard, who lags team mate and championship leader Kimi Raikkonen by 23 points after seven races, said: "The new car is quicker but we have to wait until it has developed reliability and then we will have it racing.
"From Kimi's point of view, to lead the championship at the moment knowing that another car is coming which is going to be an improvement gives him a great opportunity."
Coulthard said the single lap qualifying format, introduced this season to make racing more exciting, was causing him problems.
"Clearly I am making my weekends difficult by qualifying poorly and that is the area I have got to focus on," he said. "The rest is easy, I have done enough to know how to handle it."
"I am here to win this Grand Prix as I have been at all the others," added the Scot, who won the opening race in Melbourne. "If I get the qualifying right then I will have a good chance."
