Despite having configured it so, my W510 does not hibernate when I close the lid - it stays on.
Ensure you have checked both the Lenovo Power Manager settings, as well as the Windows Power management settings to see if they are consistent. In particular, check the Lenovo Power Manager Power Plan particulars for Idle Timers, Enter System Hibernation to make sure that Hibernation is not turned off for the AC vs. Battery power plan you are using.
In power manager, ensure that the lid close event is configured for hibernation. Double click the Lenovo Power manager battery Icon on the tool bar and follow the link for setting what action closing the lid triggers.
Check Windows power management :
Start-> control panels -> power management
Select advanced tab, and select hibernate as the action taken when lid closed. OK to exit.