Its the run-flat tires. This magazine has testet several new 5ers before without any problems. Other carmags has done the same.
So its tires and maybe this particular car had calibrated the ESP wrong but I say the mainproblem are the tires cause this hasnt happen before when they tested the 5ers.
However its good its a carmag that found the problem so hoefully the maker of this tires are getting homework and deliever us better tires.

I also know many owner changes their run-flats to "real" tires cause they wasnt satisifed with the run-flats.

Im happy the car didnt flip over like A-class