BMW claims engine revisions to its Mini Cooper D planned for later this year will make the diesel hatch capable of an impressive 72.4 mpg.

The Cooper D is already BMW's cleanest ever car, but the improvements to the 1560cc diesel unit will mean the car's CO2 output will drop by nearly 12 per cent from 118g/kg to 104 g/km.

Combined fuel consumption will increase by nearly 13 per cent, from 64.2mpg.

The reduction in fuel usage and emissions will be achieved using a Brake Energy Regeneration, Auto Start-Stop Function and Switch Point Display package that will come at no extra cost.

The Brake Energy Regeneration system uses an Intelligent Alternator Control (IAC) and an Absorbent Glass Mat battery to recycle energy that would previously have been lost, saving fuel.

The IAC reduces drag on the engine by only engaging when required to charge the battery, and the energy generated by the engine under braking or descending a hill is utilised by the IAC to charge the battery instead of being wasted.

The Auto Start-Stop Function is available with the manual transmission cars and automatically switches the engine off when the car is stopped or in neutral.

Pushing the clutch in restarts the engine, and the system may be de-activated at the touch of a button when not required.

The Switch Point Display also aids drivers of manual transmission cars by selecting the most economical gear. The engine management will analyse the speed, road situation and throttle before displaying the ideal gear on the cockpit display.

The new technology will be available on models across the range from August, and although it is the diesel that will see the best results, the Mini One will also see an improvement of 6.5 per cent fuel consumption, the Cooper an improvement of 6.9 per cent and the Cooper S 10.3 per cent.

MINI Cooper D owners will continue to benefit from the car falling into VED tax band B. Little wonder then that MINI UK is again celebrating a month of record car sales. In the month ending April 30, 3,729 were sold, compared with 2,780 in the same month last year.