Thank you for your question.
In order to use sleep mode, you have to set "Ignition source" to ---> "External voltage" and you need to set "Low Voltage level" to something like "13000"
In that case, if you are using 12V power, device will be in sleep mode when the vehicle is turned off (voltage under 13V).
When the vehicle is ON(voltage higher than 12V) the device will exit sleep mode.
Latest firmware version for FM5300 is 01.07.79. If you want to use it, please contact your sales manager.