The progressive metamorphosis of the Mercedes-Benz A-Class, from a cleverly packaged box on wheels into a conventionally formed luxury hatch, is no doubt one of calculated execution.

Not only has it seen the original ‘baby Benz’ become increasingly competitive against the established premium hatchback set, but the transformation has also granted its previously unloved B-Class sibling some much-needed breathing room, allowing it to fashion itself a more distinct, confident identity within Mercedes' small-car line-up.

The original B-Class of 2005 was, in essence, an extended version of the second-generation A-Class. But as the contemporary A-Class offered a comparatively superior drive with only a small compromise on cabin space, the ill-proportioned B-Class fell flat with critics and buyers alike.

In 2011, the second generation of this compact MPV gained a new platform (later shared with the third-generation A-Class), a boost in premium appeal, a more coherent exterior design and even greater interior versatility. Unfortunately, unimpressive road manners and poor refinement were arrows to its Achilles heel.

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Now the B-Class is back for a third generation. And while the mechanical similarities to its hatchback sibling are as strong as ever, the chances of that relationship bearing fruit have never been so promising. To say the fourth-generation A-Class is the most convincing iteration of the breed we’ve seen in its 22-year history is no overstatement.

As with its sibling, the B-Class’s cabin has had its luxury credentials amplified, while driver assistance features have also trickled down from the S-Class limousine. Meanwhile, a new platform and engine line-up might just remedy the shortcomings that marred its predecessor. But have these changes finally allowed the B-Class to rise above the relative mediocrity that’s characterised its existence thus far?

Price £26,975 | Power 134bhp | Torque 148lb ft | 0-60mph 8.4sec | 30-70mph in fourth 11.5sec | Fuel economy 32.9mpg | CO2 emissions 126g/km (WLTP) | 70-0mph 45.9m

MERCEDES-BENZ B-CLASS RANGE AT A GLANCE

Mercedes offers seven flavours of B-Class: four petrols and three diesels, all turbocharged and with a capacity no larger than 1950cc.

Unlike in the A-Class, whose more powerful models compete with the best hot hatch rivals, there are no plans to bring an AMG-badged B-Class to market, so the quickest car is the B250, which will hit 62mph in 6.4sec.

That price jump beyond the B200d is because, from the 250 onwards, AMG Line is the most basic trim level and brings an independent rear axle rather than a torsion beam.

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