Available only with the 74bhp 1.0-litre engine in SE specification, the automatic-equipped Mii returns 62.8mpg and 105g/km. That’s compared to 60.1mpg and 108g/km for the manual.
Acceleration in the Mii auto is slightly worse, though, with the 0-62mph time increasing from 13.2 seconds to 13.9 seconds.
The gearbox itself is an automated version of the manual five-speed and weighs only 3kg more than the manual gearbox.
Buyers can order the Mii auto as a three or five-door model, priced at £10,390 and £10,740 respectively – that’s an extra £1,115 over the manual.
The first automatic-equipped Miis will be available in November.