Hybrid cars are becoming more popular because they use less fuel and produce fewer harmful emissions. Engineers are working on making hybrid cars more affordable for everyone. A new prototype hybrid powertrain for a small car with a diesel engine is being tested. The goal is to find the best way to control the powertrain to save fuel and money when driving in cities. The test results will be compared to computer simulations to make sure the control program is working correctly. The research shows that the simulation program is accurate and can help make hybrid cars even more efficient.