You can see in this video the Porsche 936 on the Mulsanne straightaway reaching almost 400 km/h(or almost 250mph).

Mulsanne is the famous straightaway on the Circuit de la Sarthe that is used in the sports car endurance race 24 Hours of Le Mans. Originally a 5km straight, it was reduced into 3 sections with two chicanes to reduce the dangerous 250mph speeds for the 1990 endurance race.

This is Porsche 936, a racing car introduced in 1976 by Porsche to race in Le Mans.From 1976 to 1981, the factory entered Porsche 936 won the 24 Hours of Le Mans three times with Jacky Ickx ('76, '77, '81), and came second twice ('78 and '80).