Design ingestion for 20 million vehicles producing 600-byte records each second (~40 TB/hour). How should vehicles send data to GCP?

Publishing data directly to Google Cloud Pub/Sub is the most scalable and efficient solution for this high-volume, real-time ingestion scenario. Pub/Sub is designed for massive-scale event ingestion, decoupling producers from consumers, and handling fluctuating loads without data loss. Writing directly to Google Cloud Storage is inefficient for continuous, small record streams as it incurs high I/O operations and latency. Streaming directly into Google BigQuery from vehicles is not ideal as BigQuery is an analytical database, not a real-time message broker, and direct ingestion from millions of devices would be complex and costly. Continuing with an FTP-based system is unsuitable for real-time, high-throughput data ingestion due to its inherent latency, lack of scalability, and operational overhead.