In summary, I achieve an EPA city estimate of 23, reaching 26, and align closely with EPA highway estimates of 31, frequently attaining 32, as shown by the vehicle's computer. HOWEVER! The Fuelly app does not provide a city-specific reading. I typically get 29.3 miles per gallon, with around 30% of my driving in urban areas and 70% on highways. I have achieved fuel efficiencies of 32 mpg and 34 mpg, mostly on highways.
It is possible that some of the aforementioned statistics represent UK miles, which are shorter than US miles, resulting in greater MPGUK values. I own a 2024 Countryman S All4 with an automatic gearbox. I use it very cautiously, usually at the upper limit of the accelerator pedal in eco mode. Upon first purchase, I undertook a 120-mile journey using hypermiling techniques, achieving 34 miles per gallon (US) as shown by the onboard computer. I replaced the tires with non-runflats (Michelin Cross Climates for 2,000 miles and Continental DWS for 4,000 miles). Since June 2024, I have recorded fuel use for 3,000 miles with a 30% city and 70% highway driving ratio using the Fuelly application. Overall, I get 29.3 miles per gallon according to Fuelly, and 31.3 miles per gallon as shown by the vehicle's computer while driving very cautiously. The disparity between Fuelly and the MINI is more apparent when the MINI indicates 32+ mpg, sometimes reflecting a discrepancy of 4.7 to 4.8 mpg. The average difference is 1.6 mpg, whereas the mean is 2.3 mpg.