Furthermore, ELS is primarily intended for use within the single player mode of GTAIV. Thus, except for the sirens (the functionalities of which are altered and reduced in multiplayer for compatibility reasons), none of the ELS features are synchronized for other players during online play. This does not mean that ELS cannot be used in multiplayer. However, due once more to the inner-workings of GTAIV, although flash patterns may appear normal to the user, they will appear much slower or not at all for other players. Environmental lighting and other features will not be seen at all by others. A slight workaround is to ensure that the Els_Ai_Mp feature in the ELS.ini is set to on. This will allow ELS to animate the vehicles of other players as it would those of the AI (artificial intelligence) police in single player. Note, however, that these vehicles will only be detected when their sirens are active—therefore vehicles that do not possess sirens will be ignored.

 

 Note: For synchronicity purposes, in multiplayer, the ELS siren and functionality are slightly altered.

 

From ELS User Guide.

Four cars? That shouldn't happen! You are putting both the .ini file and the .net into the scripts, right? Also after you have places the files in your scripts folder, go to the ini and make sure you have 20 cars listed.

From ELS User Guide.

Indeed as mentioned earlier, but kids these days are too lazy to read things :P