BMW has revealed a range of performance enhancements to be made available on the new 4-series coupé from early 2014.

The range is part of its M-Performance line of retro-fit options – in the process providing the first tacit clues to the appearance of its upcoming M4, the successor to the recently discontinued M3 coupé. Autocar can reveal the car is now slated to make its world debut at the Detroit motor show in January 2014.

As with similar packages made available with other recent new BMW models, the 4-series M-Performance package consists of an aggressively styled body kit, various interior trim upgrades, a series of detailed suspension tweaks, new 20-inch wheels and tyres. There's also a subtle increase in power and torque ratings for three of the four engines UK buyers are able to choose with the 4-series coupé.

Customers can opt for the complete package or individual items – all of which are available on a retro-fit basis through official BMW dealers.

The new M-Performance body kit, which is said to closely preview the look BMW will adopt on the upcoming M4, has been styled and developed by BMW’s M division and brings a number of comprehensive changes to the appearance of the new 4-series coupé.

They include a deeper front bumper complete with carbonfibre splitter element and enlarged air ducts, LED imbued Xenon headlamps, blackened chrome trims throughout the exterior – including the grille, air breather trims along the flanks, window surrounds and tail pipes,  carbonfibre exterior mirror housings, body side decals, wider sills, carbonfibre boot deck spoiler and a new rear bumper with air extraction ducts and an integral diffuser element.

Inside, there is a new three-spoke steering wheel, more heavily contoured sport seats and other individual touches that BMW plans to make public at the upcoming Frankfurt motor show.

BMW has confirmed the 4-series M-Performance package adds 16bhp and 29lb ft to the 420d coupé’s standard turbocharged 2.0-litre four-cylinder common rail diesel engine, raising output to 195bhp and 309lb ft. It also brings an additional 27bhp and 29lb ft to the 428i coupe’s standard turbocharged 2.0-litre four-cylinder direct-injection petrol engine, lifting its reserves to 269bhp and 287lb ft.

The increases brought to the range-topping 435i coupé’s turbocharged 3.0-litre six-cylinder direct-injection petrol engine are even more generous, providing it with an extra 34bhp and 37lb ft to bolster its output to 336bhp and 332lb ft.

BMW confirms the lift in output in all three engines is achieved through revisions to software as well as the adoption of new exhaust systems. The result, according to the German car maker, is a “perceptible increase in performance” in all three 4-series models “without any increase in fuel consumption or CO2 emissions”.