This paper measures ‘excess’ car travel for its role in decarbonisation. On average, each English adult travels around 5,680 miles a year and emits 1,006 kg of CO2. However, the top 5% ‘excess’ car users travel 4.8 times and emit 5.7 times the national average. Four binary logistic regression analyses were used to model the probability that people with specified characteristics belong to the ‘excess’ mileage and emitter groups. Results indicated that gender, employment and socio-economic status, household income (higher quintiles), company car availability, residential location and local population density were highly significant correlates of this ‘excess’ travel mileage. Multiple car ownership, business travel by car, multiple international flight frequencies and ownership of larger and diesel cars were positively associated with excess travel and emissions. A mileage rationing scheme targeting the top 20% users can cut emissions substantially (by 26%) compared to targeting ‘excess’ (top 5%) users only.