Mercedes-Benz UK says its new ECO SE models, available from January 2014, will feature weight-saving measures, powertrain refinements and improved aerodynamics.
Replacing the current A 180 CDI SE, CO2 emissions on the new A 180 CDI ECO SE have been reduced by 6%, to 92g/km, with combined fuel consumption increased to 78.5mpg, compared to 74.3mpg on the outgoing model.
Emissions on the new B 180 CDI ECO SE have been reduced by 9% to 98g/km CO2, with the combined mpg 8% better than the outgoing model, at 74.3mpg.
Despite the focus on economy, the power, torque, top speed and 0-60 time remain unchanged for both models.
The A 180 CDI ECO SE is priced from £21,965 on the road and the B 180 CDI ECO SE from £22,950.
In addition, the four-wheel drive system first seen on the CLA 250 4MATIC will also be available on the A- and B- Class from January.