SEAT has improved both the economy and model choice of its city slicker the Mii.

The new Auto spec grade, which adds an automated manual gearbox, is 2.7mpg more fuel efficient on average than the Mii Sport, which has the same 1.0-litre 75PS engine with a manual gearbox.

And emissions are slightly lower too, meaning that in addition to an average fuel consumption of 62.8mpg, the Spanish brand's smallest model carries a 105g/km CO2 rating, compared to the manual equivalent's 60.1mpg and 108g/km.

Based on the manual five-speed gearbox, the automated version does away with a manually operated clutch, instead using an electric motor linked to a pair of electromechanical actuators to handle gear changes.

The result is a gearbox with the operation of a traditional automatic transmission, but with the light weight more in keeping with a manual unit.

The gearbox is only available with the 75PS engine and in SE trim, making Mii Auto a standalone model as there are no plans to offer it with the lower powered 60PS powerplant.

Performance is only marginally affected by the loss of a manually operated clutch, with the Mii Sport's 13.2 second 0-62mph benchmark increased slightly to 13.9 seconds in the Mii Auto. Top speed remains at 106mph.

Mii Auto comes in both three and five-door body styles, priced at £10,390 and £10,740, with deliveries due in early November.

SE spec includes 14-inch alloys, leather steering wheel and gear knob, a gloss white dashboard panel, chrome dial and switch surrounds, heated electric door mirrors, air-con, remote central locking and six-speaker stereo.

Every Mii ordered before the end of September also comes with a free SEAT Portable System, the colour touchscreen infotainment unit that includes sat-nav, Bluetooth hands-free phone operation and full stereo integration.