[Carlton]

pawn Код:

new Leader = PlayerInfo[playerid][pLeader];
new member = PlayerInfo[playerid][pMember];
if(CarInfo[vehicleid][cFaction] != 0)
{
        if(CarInfo[vehicleid][cFaction] != Leader) 
        {
           SendClientMessage(playerid, COLOR_GREY, "You don't have the key of vehicle");
           RemovePlayerFromVehicle(playerid);
        }
}

Only use strcmp for strings.