1:20 Curbside Multi Media Kit of the MP4/24 GP of Australia 2009 from Studio 27

The McLaren MP4-24 was McLaren-Mercedes' Formula One car for the 2009 Formula One season. It was revealed at McLaren's headquarters in Woking, United Kingdom on January 16, 2009.

The following day, team test driver Pedro de la Rosa gave the MP4-24 its first test run at the Autódromo Internacional do Algarve.

In testing, the MP4-24 was proven slower than its rivals due to aerodynamic problems, with Lewis Hamilton and Heikki Kovalainen repeatedly at the bottom of the timesheets.
The car came under much scrutiny from team members and other critics alike. Martin Whitmarsh, McLaren team principal, said the team "had not done a good enough job". He also went on to say "We have an underdeveloped car, we do not have sufficient aerodynamic downforce and we would like to focus on rectifying that as quickly as we can."

The car was originally designed with a conventional diffuser. The MP4-24 was fitted with a modified diffuser based on similar principles to the double-decker cars at the 2009 Malaysian Grand Prix after the FIA confirmed that such components were legal, after several teams had asked the FIA to clarify the matter.