[Konstantinos]

pawn Код:

public OnPlayerStateChange(playerid, newstate, oldstate)
{
    if(newstate == PLAYER_STATE_DRIVER || newstate == PLAYER_STATE_PASSENGER)
    {
        if (GetPlayerVehicleID(playerid) == masina)
        {
            // player entered that vehicle..
        }
    }
    return 1;
}

This checks if the player enters a vehicle as driver or passenger and if the vehicleid is the one masina holds. If you want to check only for driver, change:

pawn Код:

if(newstate == PLAYER_STATE_DRIVER || newstate == PLAYER_STATE_PASSENGER)

to:

pawn Код:

if(newstate == PLAYER_STATE_DRIVER)

This one checks if the player is in that vehicle which can be used anywhere else.

pawn Код:

if (IsPlayerInVehicle(playerid, masina))
{
    // player is in that vehicle..
}