1) They only pitted older models against the latest update of Tesla's system. E.g. the 3 year old S-class was tested instead of the new E-class, which had just started to be delivered at the time. (And had been tested by car journalists for months.) At the time that S-class entered production, Tesla had not had any "autopilot" at all.

2) They tested only lane keeping. Unsurprisingly the Tesla was better at that. They did not however test automatic emergency braking, autoparking etc. - features that Tesla either simply doesn't have or isn't as good in.

tl;dr: Cherry-picked test.