What an intresting post. Sure am glad it is not my car though!

Unfortunately, I agree with Mark Elrod.

Starting with a cold system, no pressure, and run it as hot as you
like, once it cools it will return to the same volume.

As Ken rightly states, the MB system keeps all of the coolant under pressure, and accounts for the natural expansion by
the elasticity of the plastic resivoir in the loop.

The only way the pressure could increase to something greater then what was in the system on startup is if there was a leak adding pressure.

Craig Amos
1987 300D turbo
270,000 miles