engine = function(player)
 local veh = getPedOccupiedVehicle(player)
	setVehicleEngineState(veh, not getVehicleEngineState(veh))
end

bindKeys = function(player)
 bindKey (player, "J", "down", engine)
end
addEventHandler('onPlayerLogin', root, bindKeys)
addEventHandler('onPlayerJoin', root, bindKeys) -- guest player ise yine de bindlesin.