Which cars \ exact models have more pack reserve? Do you have any references on this?
Chevrolet Volt first model had a 16kWh battery of which only 10.3kWh was available. Not a BEV though, a lowly PHEV.
There are quite a few sources, here is one on the E-tron that walls off 11.5 kwh from the battery pack for safety/deg margin. Tesla has a much smaller walled off % and let's users have more control over how they treat the battery (i.e letting us charge to 100% whereas 100% in a porsche/audi is really more like 90%)
Why No One Is Beating Tesla's Range