In 2005, Yamaha celebrated its 50th anniversary and was determined to excel in MotoGP. Going into their 4th year of MotoGP, the YZR-M1 was improved for the 2005 season. The improved features included a 4-stroke inline 4-cylinder 990cc engine that increase top speed and fuel efficiency the previous five valve configuration. The bike layout was made more compact by shortening and repositioning the clutch as well as repositioning a centrally-mount cam-driven gear. The fuel tank was modified to have a lower centre of gravity and the rear shock attached to the crankcase to provide better handling and stability. The 2005 Yamaha YZR-M1 was hailed a great race bike after the landslide win at the 2005 MotoGP World Championships. Driven by Valentino Rossi, the Yamaha YZR-M1 claimed the world title with a 147-point margin over Marco Melandri from Honda Racing.