The difficulty here lies with the fact that Trek uses a different testing methodology, including a spine analog. (From the short marketing video, the tests Trek has used to determine the efficacy of this new helmet indeed seem much more sophisticated.) So it could very well be that the advantages are not revealed in the test MIPS uses. According to Virginia Tech’s helmet rating, the WaveCel is indeed the best-performing helmet, but in second-place is an older Bontrager helmet with a MIPS liner. (Plus, they use an arbitrary quantitative score to rate helmets.)
However, Trek should have anticipated this and been either more cautious than saying “48 x more effective” — which is marketing BS unless you put it in the proper context. Even if you do, you would talk past most people and you would still be left with a fantastic claim. Trek should now work with MIPS and other industry-leading research institutions on helmet safety to improve testing procedures in general. Because the situation could really be analogous to early crash tests that led to car companies optimizing for crash tests that were not representative of most accidents (e. g. running 100 % coverage tests rather than partial coverage tests, and using a rigid structure instead of one that deforms).