The progression of most motor manufacturers generally comes in small, evolutionary steps.

Only so often each decade does a new model launch become a historic event for a brand.

Ford achieved it when the curvy Sierra replaced the three-box Cortina in the 1980s.

In the 1990s the Boxster put Porsche within reach of a whole new customer demographic.

Kia did it in the 2000s when its European-designed Cee’d replaced the forgettable Cerato.

The new A-Class is just as important a car for Mercedes-Benz.

The German brand replaced a car which appealed to the middle-classes reaching retirement with a new model focused on attracting those still climbing the corporate and social ladders.

An initial glance at the latest addition to AM’s long-term test fleet, this A220CDI AMG Sport, reveals a lot of promise.

The AMG bodystyling and metallic blue paintwork give an aggressive edge to a car that already looks far more interesting than a BMW 1 Series or Audi A3. 

Under the bonnet sits the most powerful turbodiesel offered in the A-Class, a 2.1-litre unit developing 168bhp and 350Nm of torque.

Coupled to a seven-speed dual clutch automatic transmission, it’ll propel the car to 62mph in little more than eight seconds, but more importantly it never runs out of breath in A-road overtakes.

It is surprisingly noisy however, possibly some evidence that not all the refinement associated with Mercedes-Benz saloons can filter down into the cars with lesser price tags.

Not that the price tag of our test car is particularly modest. In a model range starting at £18,970, the A220CDI is positioned as the range-topping diesel so comes in at £27,170.

It is suitably equipped with premium features, including air-con, 18in alloys, artificial leather upholstered sports seats, tyre pressure monitor, ambient lighting automatic lights and wipers, cruise control and a start/stop function which helps keep CO₂ emissions down to 115g/km so it’s only £30 for road tax.

Safety is emphasised too. It has a maximum five-star EuroNCAP rating thanks in part to integral systems such as numerous airbags, adaptive brake assist, a driver fatigue alert and a collision prevention assist system which warns the driver if it senses the car is gaining too quickly on the vehicle in front so they can apply the brakes.

However, the car we’re testing during the next six months is an absolute technology showcase and carries almost £10,000 of optional extras.

The single most costly of these is the Comand Online system with media interface at £2,100, which encompasses a seven-inch tablet-style colour display, hard disk drive navigation with 3D maps and speed limit assist, voice control and in-car internet access through the user’s mobile phone plus a 10GB music register and SD card slot.

The other options range from the highly useful to the highly cosmetic.

Active park assist with parktronic (£690) plus a reversing camera (£300) should make it a doddle to park outside the shops.

Motorway journeys should prove a chance to try out the distronic plus (£880) adaptive cruise control plus blind spot assistance and lane-keeping assist (£770 in a combined package)

We’re looking forward to putting all of these to good use over the coming months.