¿how can i save my best lap in a practise and show while i am driving in order to compete with "myself"?

It's not possible. But you can "compete" with other players in hotlap mode.

thanks

Quote from nsblenin :

¿how can i save my best lap in a practise and show while i am driving in order to compete with "myself"?

The hotlap analyser is the closest you can get to that in LFS ATM.

http://www.lfsworld.net/rafa/