Measurements have been made of the fuel consumption of a petrol and a diesel automobile when starting from the cold. The cars were the 1. 1 liter petrol VW Golf and the 1. 5 liter diesel version, which have the same passenger accommodation and nearly identical road performance. It was found that the diesel automobile used less fuel in the 'warm-up' period than the petrol, both when being driven at constant speed on a test track and with the engine idling and the car stationary.