Mercedes was recently caught on camera in Finland hatching a new A-Class (W177), seen here as a heavily disguised prototype with a very low ride height. It suggests engineers were honing the car's suspension ahead of its big debut, supposedly scheduled to occur at some point in 2018.

Despite the bulky disguise, we already can see the test car was wearing production body and lights. It looks slightly wider and longer than the current A-Class, and will offer latest-generation lighting tech. At the front, the test vehicle’s halogen lights will only be installed on the lower-spec versions of the range, while the more expensive ones will employ a more sophisticated full-LED setup. The different shape of the taillights is already noticeable and these appear to be significantly wider to better reflect the car’s increased footprint.

2018 Mercedes A-Class render

The jump in size will pay dividends not only in terms of rear legroom as a result of the stretched wheelbase, but will also mean the boot can be enlarged. Today's 341-litre boot lags car such as the Volkswagen Golf and, generally, the A-Class is off the pace in terms of practicality. 

Thanks to Mercedes’ second iteration of its flexible Modular Front Architecture (MFA), the new model will actually lose some weight despite growing up. Previous spy shots have shown a prototype packed with sensors and cameras, thus hinting the new A-Class will feature a lot of safety and assistance systems.

As for interior goodies, we’ll have to wait a little while longer to catch a glimpse of the overhauled cabin. Chances are an all-digital instrument cluster is going to be offered — at least as an option — to better rival the A3 Sportback and its high-tech 12.3-inch Audi Virtual Cockpit.

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An assortment of three- and four-cylinder turbocharged engines is going to be available, topped by a 2.0-litre unit with more than 400 horsepower in the flagship A45. Sitting below the cream of the crop will be a warm version to fill in the huge gap between the A250 and the A45: currently, there’s a 163-hp difference between the two. Not only that, but the A45 is also roughly £12,000 more expensive than the A250 AMG, so there’s certainly enough room between the two for a new hot hatch.

The A-Class family is set to expand with the fourth generation, because Mercedes has plans to introduce a saloon. Previewed by the Aesthetics A sculpture, the new addition to the range will sit alongside the CLA rather than replace it. If the rumour mill is correct, a concept to preview the posh compact sedan will debut next month at Auto Shanghai in China where a long-wheelbase derivative will allegedly be offered.

Photos: Automedia

Gallery: 2018 Mercedes A-Class new spy photos