Server Side

local plrVehTable = {}
local curArg

function setVehStatus(plr)
    if (getElementDimension(plr) ~= 336 or not hasObjectPermissionTo(plr, "command.em", false)) then
        return false
    end
    if (not curArg) then
        local vehs = getElementsByType("vehicle")
        for i, veh in ipairs(vehs) do
            if (getElementDimension(veh) == 336) then
            local driver = getVehicleController(veh)
                if (driver) then
                    plrVehTable[driver] = veh
                else
                    destroyElement(veh)
                end
            end
        end
        curArg = true
        outputChatBox("Enable vehicle auto-remove feature and removed all unoccupied vehicles with successfully!", plr, 0, 255, 0)
        outputChatBox("Warn: If you add new vehicle and it's unoccupied, it won't be auto-removed!", plr, 0, 255, 0)
        removeEventHandler("onVehicleExplode", root, setEMVeh)
        removeEventHandler("onVehicleExit", root, leaveVeh)
        removeEventHandler("onElementDataChange", root, onPlrLeaveEMDim)
        addEventHandler("onVehicleExplode", root, setEMVeh)
        addEventHandler("onVehicleExit", root, leaveVeh)
        addEventHandler("onElementDataChange", root, onPlrLeaveEMDim)
        return true
    end
    plrVehTable = {}
    outputChatBox("Disable vehicle auto-remove feature.", plr, 0, 255, 0)
    curArg = nil
end
addCommandHandler("emuvehrem", setVehStatus)

function setEMVeh()
    if (getElementDimension(source) ~= 336 or not curArg) then
        return false
    end
    local driver = getVehicleController(source)
    if (not plrVehTable[driver]) then
        return false
    end
    plrVehTable[driver] = nil
    destroyElement(source)
end

function leaveVeh(plr)
    if (getElementDimension(source) ~= 336 or not curArg) then
        return false
    end
    if (not plrVehTable[plr]) then
        return false
    end
    plrVehTable[plr] = nil
    destroyElement(source)
end

function onPlrLeaveEMDim(dName)
    if (getElementType(source) ~= "player" or dName ~= "e" or not curArg) then
        return false
    end
    local curKey = getElementData(source, "e", true)
    if (curKey) then
        return false
    end
    destroyElement(plrVehTable[source])
    plrVehTable[source] = nil
end