The MPG Paradox: Why car purchasers say they care about fuel economy, but don't

Previous research undertaken by the authors revealed car purchasers generally claim fuel economy is important, but do not reflect this in their car choice. This was termed the ‘mpg paradox' (miles per gallon (mpg) being the custom metric in the UK). This paper reports on a study in the summer of 2008 which examined whether this paradox still exists and how systematically new or second-hand car purchasers consider information on fuel economy and carbon emissions.

Based on in-depth interviews with recent car purchasers, the research concludes that the mpg paradox still exists - but it has changed in nature. Whilst there is now strong evidence the car market is responding to rising fuel costs and increased choice, the ‘mpg' metric itself is not conceptually driving behaviour. Instead, simplistic rules are used to decide on what is ‘good' or ‘bad', taking little notice of information provided on the fuel economy label. The mpg metric is complex as it does not map easily on to the way in which people experience their fuel costs - i.e. the cost to fill up a fuel tank or travel a certain distance. Consequently, it is rarely used by motorists to calculate future costs or to systematically compare vehicles. Moreover, only a minority of consumers were aware of their official CO2 figures even though the UK has recently strengthened the link between circulation taxes and carbon emissions.

Most car buyers believe the only route to better fuel economy is through a smaller car, a new car, or switching to diesel. There is little awareness of the additional benefits to be gained from ‘best-in-class' comparisons. The paper recommends new information is provided to enable comparison of running costs based on how car buyers conceptualise fuel economy. This information should ideally be updated as available models and fuel prices change and could be an interactive web-based tool also available at the point of sale.