This paper presents results from a study to measure the separation of the driver's head and shoulder to various internal features of the car. Drivers were filmed whilst driving in general traffic flow, hence were unaware that they were involved in a study. The results show that certain sub-groups of the driver population are likely to be more at risk for certain impact types. Small females are considerably closer to the steering wheel than the rest of the population, and therefore prone to head strikes in frontal impacts. Large males are likely to interact with the cant rail and 'B' pillar in side impacts.