What's the news?

The Mercedes-Benz A- and B-Class families are soon set to grow with the announcement of Eco and 4Matic versions of each model. Visually the cars remain largely unaltered, but under the bonnet changes have occurred to open the models up to a wider target audience.

Beginning with the Eco models, the 1.5-litre diesel engine found in both the A 180 CDI SE and B 180 CDI SE has been upgraded to produce a better fuel economy and reduce emissions without compromising on power. As such the new A 180 CDI Eco SE now manages 78.5mpg compared with the 74.3 figure of the outgoing engine, with emissions down to just 92g/km. The B 180 CDI Eco SE returns similar figures: an eight per cent improvement on economy to 74.3mpg and a nine per cent reduction in CO₂ to 98g/km. These achievements result in two cars that qualify for free road tax as well as savings at the pumps.

In addition to the revamped engines, both models have gone through some subtle styling changes in order to achieve these new figures. Both cars have had their front grilles streamlined, their ride height dropped and underbody panelling installed. They've also been fitted with a lightweight fuel tank, longer ratio gearing on the higher gears and an improved energy regeneration system.

These new fuel-friendly versions are to be launched in conjunction with all-wheel drive models, too. The A 250 4Matic and B 220 4Matic both feature the same all-wheel drive set up that was debuted on the CLA 250 4Matic not so long ago. The 4Matic system uses an electro-hydraulically controlled multi-disc clutch to ensure that power is always sent to the place with the most traction, allowing up to 50 per cent of power to be sent to the rear wheels.

In terms of trim, the A 250 4Matic can be had in both AMG Sport and Engineered by AMG guises; while buyers of the B 220 4Matic are limited to just the Sport trim level.

Anything else?

All these new models are to be added to the Mercedes-Benz catalogue in January 2014. Prices for the A 180 CDI Eco SE start from £21,965; and you'll need £22,950 for the B 180 CDI Eco SE. The A 250 4Matic comes to market from £28,985; while the B 220 4Matic costs upwards of £28,135.