The concept of the Software Defined Vehicle (SDV) has recently been attracting significant attention. An Open SDV, which allows third parties to develop and provide applications that directly interact with vehicle systems, holds strong potential to enhance both the value and appeal of vehicles. This talk discusses the possibilities and challenges of realizing such an Open SDV ecosystem that enriches the driving experience and vehicle functionality. In particular, it introduces the Vehicle API being developed under the Open SDV Initiative, which aims to address one of the key challenges in this domain. The talk will explain the background and design principles of the Vehicle API, as well as its technical structure and implementation approach, from an engineering perspective.