While I did not have the chance yet to compare an X to the BMW offerings, it is a notable fact, that Tesla in the meanwhile for both the X and the S is working with the same German companies which supply BMW and Audi. The interior of the X is made by a company usually doing Audis, and the suspension is made by Continental. They also have Bosch components, Harman audio etc. That should put them quite close in quality to the German brands.