McLaren are hoping the MP4-19B will rescue their season

The team have endured a poor season so far but are hoping the new car will see them challenging for podium places.

Driver David Coulthard said: "It is a positive move and I am looking forward to seeing how it goes this weekend."

Fellow McLaren star Kimi Raikkonen said: "It has run well in testing and I hope it will be as reliable in the race at Magny-Cours."

The new car should represent a major step forward over the troublesome MP4-19, which has been both slow and unreliable so far this season.

McLaren have built a new chassis, made significant changes to the aerodynamics and modified the oil system in a bid to improve the reliability of the Mercedes engine.

We believe that the MP4-19B is a step in the right direction from both a performance and reliability perspective Martin Whitmarsh McLaren managing director

Its pace and reliability seemed good in testing in Jerez in southern Spain last week, even though it was pipped to the fastest time by BAR driver Takuma Sato.

McLaren managing director Martin Whitmarsh said: "During the test we completed comprehensive chassis- and engine-proving programmes alongside France-specific set-up and tyre work.

"We believe that the outcome from both a performance and reliability perspective demonstrates that MP4-19B is a step in the right direction, which is why the decision to race the car has been made.

"The entire team is continuously working to improve our overall package and while the MP4-19B is a significant part of this process, additional developments are already planned for the coming weeks and months."

The new car's performance will be watched closely by both the team and outside observers, who will be looking at it as an indication as to whether McLaren can extricate themselves from a slump.

Analysis: McLaren stalled in F1 slow lane

Although the team came close to winning the championship in 2003, they were forced to use a modified version of their 2002 car because their new car, the MP-18, was not ready.

When it did appear in the summer after a series of delays, it was too unreliable ever to race.

The MP4-19 with which McLaren started the 2004 season was, according to technical director Adrian Newey, "a de-bugged 18".

Sources in McLaren now say it was a mistake not to design a new car for the start of the season.