McLaren hope the MP4-19B will turn around their fortunes in what has so far been a disastrous season.

BBC: Pedro de la Rosa in the McLaren MP4-19B at Jerez in Spain

The MP4-19B had revised aerodynamics and rear suspension but still bore some of the compromises inherent in the MP4-19.

BBC: Remarkable turnaround

The 19B is heavily revised, with a new chassis and fundamentally redesigned aerodynamics and extra features aimed at reducing the fragility of its Mercedes engine.

BBC: Pedro de la Rosa in the McLaren MP4-19B at Jerez in Spain

The team will decide whether to give the new MP4-19B its race debut at the French Grand Prix on 4 July after this week's test at Jerez in Spain.

BBC: Pedro de la Rosa in the McLaren MP4-19B at Jerez in Spain