i am a demo player of LFS , but after creating an account my stats in the lfsworld.net are still zero, even after several on-line races

Your races only get counted, when you have a S2 licence.

But you can upload hotlaps on the demo combos.

but when i press 1 in hotlapping i get "replay not recorded" message every time

I guess, you have the option for recording replays set to "never" then.

Change it to "manual save"; dont really know, where the option is; I think, under "Game".

Isn't it the 2 key to save replays? When hotlapping I just go Esc > Replay

yes, the 1 key plays the replay, the 2 key saves it

There's an option to automatically record replays somewhere. Switch that on and you'll be able to use the 1 and 2 keys to save the replays.

I always thought, 1 gives the replay an automatic name like "spyr_BL1_XFG_1:34.964".

I think you're right

yeah - you are.

so pressing 1 or 2 stops the current race?

No, just records the replay into an spr / mpr file.

after the replay is shown is it possible to continue the race?

Pretty sure it is. I think when you save mid race you can just carry on.

why does the replay repeat over again? that leaves no option but to restart or end the race.

Quote from spyr :

why does the replay repeat over again? that leaves no option but to restart or end the race.

Sorry, I don't get what you mean.

I think he means that in single player games, as soon as you play the replay the game is over and you can't continue from where you were.

The thing about the replays is that they're not like video recordings - LFS calculates the physics every time, as if someone was playing. That would make it kind of difficult to go from real player to "virtual" replay player, then back to real player again afterward.

The replay system isn't fantastic, the only real application it has is for improving lines and as has been said above - entering hotlaps