Automotive Electronic Control Units (ECUs) are usually the most complicated and powerful embedded systems in an automobile. Verification and validation of these ECUs poses challenges due to exponential growth in the size and complexity of ECUs's software. This paper provides a new functional complexity metric that can be derived from the specification and can be used to estimate the total number of test cases required. Further, ECUs need to be verified and validated in accordance with their operational profile. Testing with operational profile will be cost effective with better reliability confidence. At the same time operational profile based testing can speed-up the V&V process by allocating the resources in relation to use and criticality. In this paper, the operational profile method is applied, as a case study, to the front and rear fog light ECU. Methods for deriving function points, functional complexity, computing the number of test cases, developing operational profiles, and test case allocation are presented. Additional benefits are also shown by integrating the functional complexity metric with the operational profile.