Mercedes has revealed the first official pictures of its all-new upper medium C-class.

Due on sale in mid-2014, the new model will emit 103g/km and return an official 70.6mpg in C220 Bluetec CDI guise.

That’s a 6g/km drop from the outgoing model’s low of 109g/km and puts it ahead of its chief rivals, the BMW 320d Efficient Dynamics at 109g/km and the Audi A4 2.0 TDIe at 112g/km.

Visual changes bring the C-class more into line with fresher models in Mercedes’ range, such as the E-class.

The new model is also 95mm longer than its predecessor and has an 80mm longer wheelbase, which, according to Mercedes, creates extra legroom for rear seat passengers.

The boot is also slightly bigger at 480 litres versus the current C-class’s 475.

In addition to the headline 170hp 2.1-litre (C220 CDI) diesel engine, the C-class will be available with two petrol engines from launch.

The C180 will feature a 156hp 1.6-litre petrol unit with 116g/km and 56.5mpg, while the C200 184hp 2.0-litre unit will offer 123g/km and 53.3mpg.

A diesel hybrid version will also become available later on. Known as the C300 Bluetech Hybrid, it will be fitted with the same 204hp diesel engine and 27hp electric motor drivetrain as the larger E- and S-class models and is expected to return an official 72.4mpg.

Further engines are also due, including a new 1.6-litre supercharged diesel unit with 115- or 136hp. Mercedes is yet to reveal economy or CO2 figures for this version but said it would be “in a leading position in its segment”.

The existing 2.1-litre diesel engine will also spawn more variants, ranging from 115- to 204hp.

Various different suspension options will be available offering harder or softer set-ups. Mercedes’ Airmatic air suspension system will also be available on the C-class for the first time.

The firm’s Attention Assist and Collision Prevention Assist systems will be fitted as standard. The former sounds a warning if the driver appears to be falling asleep and the latter is an autonomous braking system.

The usual suite of Mercedes safety systems are also available as options.

Prices will be announced closer to the model’s on-sale date.