Car dealership entity-relationship diagram modeling the complete sales lifecycle from vehicle inventory through customer transactions and payment tracking. The schema connects Vehicle and Manufacturer entities to Car Model, which branches into Car Feature specifications and Car For Sale inventory records. Sales transactions flow through Car Sold (linking customers and vehicles) to Customer Payment for installment tracking. This normalized structure eliminates data redundancy, enforces referential integrity via foreign keys, and supports complex queries on inventory, sales history, and customer payment status—critical for dealership operations, financial reporting, and customer relationship management. Fork this diagram on Diagrams.so to customize table names, add indexes, or extend with service scheduling or warranty tracking entities. The mandatory/optional relationship indicators (solid/dashed lines) clarify which associations are required versus optional, aiding database implementation and API contract design.