The maximum speed at which a car can be run on a race track with one full lap, measured in kilometers per hour (kmh). Since 2005, speeds for prototypes have been capped at 300 km/h, while GT cars were limited to 250 km/h (~155 mph) before that time. Prototype speeds will increase to approximately 350 km/h (~220 mph) in 2011 due to changes to their technical regulations.