This conference talk explores how BMW has scaled their Bazel build system for autonomous driving software development over a four-year period. Learn about the dramatic growth from one to eight Electronic Control Units (ECUs) in their Bazel workspace, and how their CI system now handles 80,000 builds daily using 37,000 vCPUs at peak. Speakers Alexander Scott and Johannes Hummel detail the current technical infrastructure including toolchains, operating systems, developer environments, and safety requirements for autonomous vehicle software. Discover the major challenges faced when scaling a build system for complex automotive applications and the innovative solutions BMW implemented to overcome them. The presentation concludes with insights into ongoing developments and future roadmap plans, serving as a follow-up to their 2019 BazelCon presentation about their initial Bazel migration.