In comparison, the Audi A3 saloon measures 4458mm long, 1796mm wide and 1415mm tall, with a 2637mm wheelbase.
Mercedes says a relatively small frontal area and the extended rear overhang of the saloon makes it highly aerodynamically efficient. It has a Cd of 0.22, beating the 0.23 Cd of the firm’s previous aerodynamic production champion, the CLA.
Inside, the A-Class saloon features the same dashboard and advanced infotainment functions as the new hatchback, including Mercedes' new MBUX infotainment system with touchscreen control and speech recognition.
Mercedes claims the saloon offers above-average shoulder, elbow and head room for front seat occupants and class-leading head room for those in the rear. Its 420-litre boot capacity, however, doesn’t quite match the 425 litres of the smaller A3 saloon.
The A-class saloon is built on Mercedes-Benz’s MFA II platform and, as with the hatch, utilises two rear suspension layouts: a torsion beam arrangement on cheaper models and multi-link system on higher-end variants.
The model will be built at Mercedes' Rastatt plant in Germany and in Aguascalientes, Mexico, at a new joint venture factory run in co-operation with Renault-Nissan.
The long-wheelbase version for the Chinese market is built at Beijing Benz Automotive in China.
Prices for the A-Class saloon are expected to start from £26,500, making it around £3000 more expensive than the rival Audi A3 saloon.
The A-class saloon is the sixth member of Mercedes-Benz’s compact car line-up, joining the A-Class hatchback, B-Class MPV, CLA coupé, CLA Shooting Brake and GLA crossover in an expanded line-up that will also include an Audi Q3 and BMW X1-rivalling SUV called the GLB by the end of 2019.