From 1980 to 1995, France was the first European country in which diesels have become more popular than gasoline cars. In addition to better performance, this preference was notably due to a much cheaper cost of use, depending on taxation on both fuel types. But the advantage of diesel technology does not clearly seem to extend to energy and CO2 savings. In this paper, French trends over the last 15 years and latest annual available statistics (2009) about both diesel ownership and use are analysed, on the basis of ParcAuto panel data source. The results especially show that, from the moment the gap between fuel prices was reduced, diesel car annual mileages have fallen faster than those of gasoline cars. A specific section summarizes the results of our work on the behavior of French households who chose to replace their gasoline car with a diesel. Detailed examination of these switching behaviors confirms that there are increases in driving associated with new dieselists.