mercedes me app is useful if you've left your car unlocked or windows open by mistake. also stores mpg info for latest journey and how much petrol you have left and your tyre pressures. new e class and other cars allow up to unpark cars using the app ! mine is a lowly c class , so doesnt .
sometimes if you have the app loaded on multiple devices , you can get out of date notifications if you've switched on a device you havent used for a while .
hope I havent misunderstood what you mean by Mercedes me portal !