9 4W H AT R O L E F O R C A R S I N T O M O R R O W ’ S W O R L D ?the GECO air app for smartphones, developed by IFPEN, whichinforms users of the level of emissions of their journeys).We can therefore imagine the development of relatively inexpensivetechnologies (well belowe100 per car), to enable each driver toknow how much pollution is generated by his journeys, accordingto actual use of the vehicle. This flow of information, available viasmartphone for drivers, could also provide input for a global database,while guaranteeing, in compliance with privacy laws, anonymity ofthe connected cars. This would have a number of advantages:• providing public authorities with detailed information on our actualjourneys, to be used in urban planning and improveregulations;• enabling users to compare their behaviours with those of others:do they pollute more, or less, and why? Such comparisons, whichlie at the heart of “soft” regulation systems based on peer com-parison(nudge84),could have an effective, non-coercive impacton behaviour.This is all the more interesting now that knowledge of the air qualityis better and is becoming intelligible to the general public. Forexample, within a geographic area, applications like the one proposedby PlumeLabs provide an air quality report, with a predictivedimension.84Nudge - Improving decisions about health, wealth and Happiness is a book by RichardThaler, economist at University of Chicago, and Cass R. Sunstein, Harvard Law Schoolprofessor. The book draws on research in psychology and behavioural economics todefend techniques to enable private individuals to make the choices that are consideredto be more virtuous, notably using peer comparison and“soft”social constraints, whilelimiting coercive approaches.