ABSTRACT
The on-the-road performance of passenger cars is often discussed in terms of kilometres driven per MJ (or other unit of energy). This does not do justice to the different payloads that different cars are certified to carry, perhaps considering the poor correlation between required, actually used and available passenger and cargo space characterizing the vehicle choice of many passenger car owners. The payload-weighed measure of performance allows a comparison of passenger cars with other road and non-road vehicles in a reasonably unbiased way. Regarding aircraft efficiency, apart from general aviation, the regular scheduled air travel is seen on average to be as energy efficient as automobile travel, when measured in relation to transport work, i.e. per person-km or per kg-km travelled.
