The M3 GTS Sedan is, of course, derived from the M3 GTS Coupe but this model is still a concept and is not sporting the full GTS assortment yet.
According to Car Magazine, power is unspecified but said to be below the 450 PS (331 kW / 444 bhp) mark of the M3 GTS Coupe and somewhere above the 420 PS (309 kW / 414 bhp) of the standard M3. Whether it's packing the 4.4 liter V8 of the GTS or is simply sporting an up-tuned 4.0 liter from the series M3, we don't know.
This M3 GTS Sedan Concept does get some parts from the production GTS, including the 19-inch alloy wheels, larger brakes, rear boot lid spoiler and the black kidney grills. The front splitter is less wide than on the GTS and the car is said to be sporting a lighter exhaust and a tuned suspension too - perhaps identical to the M3 GTS Coupe.
The M3 GTS Sedan will go to production - in limited numbers - and may ultimately come to be closer to the GTS Coupe than this concept is hinting at.