Body Structure
The 2019 BMW X4 has higher-strength steels and some aluminum in the body-in-white. BMW used an increase in the proportion of aluminum as well as high-strength and ultra-high-strength grades of steel in the body structure. The diagram provided by BMW shows aluminum elements and the door rings, rocker rails extending back to the quarter panel, both kickpans, the suspension tunnel and a roof frame crossmember are among the ultra-high-strength steel parts. Multiphase steel elements include the floorpans and roof frame rails.