Audi has launched a 'stop-start' version of the 2.0-litre TDI A3.
Power remains unchanged at 138bhp, but it now averages 64.2mpg – up from 55.4mpg on the non-stop-start version – while CO2 emissions have fallen from 134g/km to 115g/km.
As a result, company car tax liability is cut from 18 per cent to 13 per cent.
The A3 Cabriolet 2.0 TDI gets the same green technology, which boosts fuel economy from 53.3mpg to 61.4mpg and cuts CO2 emissions from 139g/km to 119g/km.
The BMW 118d, which has a similar amount of power, manages 62.8mpg and 119g/km with a manual gearbox.
Prices remain unchanged, with the entry-level A3 2.0 TDI three-door costing £18,860.