BMW says the 4-Series Coupe fitted with the M Performance package brings an extra 16 bhp (12 kW) and 29 lb-ft (39 Nm) for the 420d model which is powered by a 4-cylinder,
2.0-liter turbocharged diesel engine. The added oomph increases total output to 195 bhp (145 kW) and 309 lb-ft (418 Nm).
The 4-cylinder, 2.0-liter turbocharged gasoline engine in the 428i is also upgraded to 269 bhp (200 kW) and 287 lb-ft (389 Nm),
representing an increase of 27 bhp (20 kW) and 29 lb-ft (39 Nm).
In addition, the 435i with its turbocharged 6-cylinder, 3.0-liter gasoline engine gains 34 bhp (25 kW) and 37 lb-ft (50 Nm) for a total of 336 bhp (250 kW) and 332 lb-ft (450 Nm).
All these power upgrades are done via new exhaust systems and software tweaks.
From the M Performance Parts catalog customers will have the possibility of selecting a limited-slip differential which will be a clutch-type unit featuring a 30 percent lock-up.
It is believed the BMW M4 Coupe will be unveiled in January 2014 at the Detroit Motor Show.