They combine the Renault-sourced 109bhp 1.5-liter turbo diesel with a series of fuel-saving measures that include the use of an aerodynamic grille element, underbody paneling and lowered suspension (-10 mm front and 15 mm rear for A-Class, and 20 mm at the front and 15 mm at the rear for B-Class). They also feature manual gearboxes with longer ratios in the higher gears, an improved energy recuperation system and a lighter fuel tank
Mercedes says that compared to the standard A 180 CDI, CO2 emissions have been reduced by six per cent to 92 g/km, with combined fuel consumption increased to 78.5 mpg UK (versus 74.3 mpg on the outgoing model). On the B 180 CDI ECO SE emissions were reduced to 98 g/km CO2 or nine percent, while fuel economy jumped eight per cent to 74.3 mpg UK.
Despite the economy gains, Mercedes states that power, torque, top speed and 0-60 mph acceleration, remains unchanged for both models.
Along with the new ECO variants, Benz is introducing the four-wheel drive system first seen on the CLA 250 4MATIC, on both the A- and B-Class, again from January 2014. In particular, the A 250 4MATIC will be available in both AMG Sport and Engineered by AMG trim, while the the B 220 4MATIC, exclusively in Sport trim.
In terms of pricing, the A 180 CDI ECO SE will start from £21,965 on the road, the B 180 CDI ECO SE from £22,950 OTR, the A 250 4MATIC from £28,985 OTR for the AMG Sport trim and £30,905 for the Engineered by AMG trim, and the B 220 4MATIC, at £28,135 OTR.