For the automotive industry the styling of headlamps become more and more important. Clear lens design with facetted freeform reflector represent the status quo of modern headlamps. Additionally the available construction volume decreases and at the same time the requirements to the light distribution increases.For that reason precise simulation of light distribution in an early stage of the development is absolutely necessary. It will be shown exemplary how these methods work and why their use is strongly recommended. The results can be compared with measurements conducted on existing headlamps and demonstrate the benefit of these methods. Due to more powerful computational models and increased computer capability these simulation tools will be improved even more in the near future.