Both the 428i and 435i have a BMW M Performance exhaust system available as well. A limited slip differential (which should be standard) is the most important performance upgrade offered.
A performance suspension system and performance brake system are also offered which when combined with the limited slip differential should dramatically improve track performance.
20 inch wheels are available in two different designs as well as an 18 inch set designed for winter use.
Cosmetic options include black grills, diffuser, side sills with the M logo (damn you BMW), BMW M performance stripes to let the world know BMW just reamed the boy racer out of you, carbon splitters, carbon mirror caps, and a carbon rear spoiler.
Carbon accents to the interior along with a BMW M Performance steering wheel are also available to spruce up the inside.
Overall, a nice set of upgrades although educated readers will know there are better places to get a power upgrade than from BMW. The limited slip differential along with the suspension and brake upgrades are highly recommended.
Press release and photos below.
Following the ideal line to a more intensive driving experience: BMW M Performance Parts for the BMW 4 Series.
Model-specific BMW M Performance Parts available from the beginning of 2014 provide additional ways of authentically emphasising the sporty character of the coupé and making the driving experience even more intense. The BMW M Performance Power Kit available for the BMW 420d (+12Kw, +40Nm), BMW 430d (+20kW, +40Nm) and BMW 435i (+25kW, +50Nm) delivers a perceptible increase in power and performances, without affecting fuel consumption and exhaust emission levels. A BMW M Performance silencer system is also available for the models BMW 428i and BMW 435i. It comprises BMW M Performance tailpipe embellishers in chrome, as well as in carbon for the BMW 435i. Meanwhile the BMW M Performance limited-slip differential ensures traction-optimised power transmission on bends. Other features that boost the coupé's dynamic potential are the BMW M Performance suspension with sporty set-up, the BMW M Performance brake system with red, yellow or orange calipers and the BMW M Performance light alloy wheels. The weight-optimised forged wheels in 20-inch format are available in two design variants as well as in the typical BMW M Performance bi-colour look in Ferric Grey with burnished spoke fronts. Another new feature in the BMW M Performance range is the 18-inch winter complete wheel sets in double-spoke design.
The dynamic charisma of the BMW 4 Series can also be given greater emphasis by means of BMW M Performance components for the exterior. A black radiator grid for the BMW kidney grille, a diffuser insert for the rear apron, side sill foils with M Performance inscription, BMW M Performance side stripes and carbon front splitters, mirror caps and rear spoiler optimise the coupe's sporty appearance and aerodynamic properties. An interior ambience inspired by racing is ensured by the BMW M Performance sports steering wheel with red central marking or Race Display in 12 o'clock position as well as gear lever and handbrake handle in carbon including Alcantara gaiter. A carbon finish is likewise available for the gear selector switch of the automatic transmission. In addition, interior strips in carbon and Alcantara, high-grade steel pedals, a specially designed driver footrest and BMW M Performance floor mats are also available for the BMW 4 Series
The new BMW 4 Series Coupé with BMW M Performance Parts premieres at the IAA in 2013.