Sleep mode works fine for me in firmware 5.6. The vampire loss on this firmware version is less than 3 miles a day. But since upgrading to firmware 5.8, the sleep mode seems to be broken. The vampire loss is now 12 miles a day. I don't think the car is really 'sleeping' either, because I was able to connect to the car using the app instantly throughout the day. With firmware 5.6, there's a long wait (up to 45 seconds) to wake up the car. By the way, I have rebooted the console and it didn't help.