All of them cover the forward mounted tie-down rings.
I use the rear cargo trunk liner, and ski bag. Then you only have access to those rear mounted tie-down rings.
Had a merc CLA as a loner when heater broke down.
There those front mounted were on the sidewall.
When I got it some years ago, it would always show battery as empty every winter (below 0C). At least on android-app. Might be they stoped producing it before sw was fixed.
Car is in for change of heater ?
And its over one year ago. But at least positiv was connected directly to battery. Keep in mind that BT-antenna is integrated in module.