Germany has one of the most ambitious climate policy goals worldwide, having pledged to reduce national emissions by 40% by 2020, and 80-95% by 2050 (base year: 1990). 2015 data suggests that progress on decarbonisation has slowed, also because emissions from the transport sector have grown. Road transport, which is contributing 20.5% to Germany's CO2 emissions, has become a major obstacle to achieving the country's policy goals. This paper analyses energy use from road transport in order to provide a better understanding of emissions from this sub-sector. Data is derived from representative longitudinal household surveys as well as mobility and fuel diaries for the period 2002-2015. Analysis reveals significant growth in energy-inefficient car choices, as well as considerable differences in mobility patterns (distances driven, driving styles) and actual fuel consumption between car segments. Findings suggest that German transport policies will fail to deliver significant emission reductions if complexities in car model choices and use patterns are ignored. Both command-and-control and market-based measures will be needed to align the transport sector with climate goals, while persisting policy inconsistencies will also have to be addressed. Findings are of central relevance for EU-wide and global climate policy in the transport sector: