Le mans 24
I know that you herd about Le Mans, it is that famous 24 hours race. This is special due to the length of the race, this isn't all about speed you will have to know how to protect your car in order to last until the end.
Le Mans 24 is one of the best racing games online, try it out without but be careful it can become addicted. In order to win you will have to think about what upgrade to make and when, speed isn't the only thing you should consider while playing.