This paper explores the role of 4.0 technologies in three dimensions. First, we examine the patterns and trends in the emergence of 4.0 technologies in Europe, differentiating between technology groups (core, enabling and twin technologies). A novel feature is that we specifically focus on the digital intensity of 4.0 patents, as they show strong heterogeneity in terms of how large the share of 4.0-related technical features of the protected technology is. Second, we study the diffusion of 4.0 technologies by means of forward citations. Finally, we examine the impact of the adoption of AI technologies on firm performance. The novelty of our study is to examine the complementarity between the adoption of AI and investments in complementary intangible assets, more specifically data infrastructure. In summary, our results show that the adoption of AI does not automatically lead to productivity gains and that only firms that invest in internal complementary intangible assets do so, regardless of whether AI technologies are developed internally or external AI solutions are used. However, productivity gains are almost twice as high when internal data infrastructure investments are combined with internal AI development compared to external AI development Firms that develop AI themselves increase their productivity when they simultaneously invest in an internal data infrastructure, but not when they combine their in-house development strategy with external data infrastructure.