public OnPlayerStateChange(playerid, newstate, oldstate)
{
    if(newstate == PLAYER_STATE_DRIVER || newstate == PLAYER_STATE_PASSENGER)
    {
        new s[126], VehicleUID = GetVehicleByID(GetPlayerVehicleID(playerid));

        format(s, sizeof(s), "Wsiad?e? do pojazdu o UID %d", VehicleUID);
        SendClientMessage(playerid, -1, s);
    }
    return 1;
}

GetVehicleByID(vehicleid)
{
    for(new i = 0; i < MAX_VEHICLES; i++)
    {
        if(VehicleInfo[i][VehicleSampID] == vehicleid)
        {
            return VehicleInfo[i][VehicleUID];
        }
    }
    return -1;
}

public OnPlayerStateChange(playerid, newstate, oldstate)
{
    if(newstate == PLAYER_STATE_DRIVER || newstate == PLAYER_STATE_PASSENGER)
    {
        new s[126], vehicleid = GetPlayerVehicleID(playerid);

        format(s, sizeof(s), "Wsiad?e? do pojazdu o UID %d", VehicleInfo[GetVehicleByID(vehicleid)][VehicleUID]);
        SendClientMessage(playerid, -1, s);
    }
    return 1;
}