In Mercedes-Benz we offer APIs for business customers which provide them with real-time diagnostics and status data of their Mercedes-Benz vehicles. The talk will be about how we have successfully used Kafka as the customer facing interface for our Push API, achieving the Best Automotive API 2022 (API:World) and our lessons learned after 2 years in production. Moreover, we will discuss how we used OAuth Authentication in Kafka to offer the same authentication mechanisms for our Push APIs and for the ordinary REST APIs. We will also see our unified API Documentation using OpenAPI and AsyncAPI and how we documented the kafka servers, topics and payloads using AsyncAPI. Finally we will discuss some challenges and decisions in order to keep our kafka-based Push API at scale, e.g. topic architecture (number of topics, partitioning, etc.), allowed consumer groups, etc.