The McLaren MP4-20 is a Formula One car that McLaren Mercedes used for the 2005 Formula One World Championship. The MP4-20 was the last McLaren F1 car to use a V10 engine due to the regulations banning V10s after 2005.

The MP4-20 was also the last McLaren F1 car to use West tobacco advertising, with McLaren to a non-tobacco paint scheme for the first time in the Hungarian Grand Prix that year due to the European Union ban on tobacco advertising coming into effect on 31 July 2005.