BMW has unveiled the M4 GTS concept ahead of this weekend's Pebble Beach car show.
While a concept in name, the GTS appears to continue BMW's recent tradition of showing a production-ready car, then simply adding 'Concept' and denying any plans for production.
The most obvious modifications are to the exterior, with a carbon-fibre bonnet, driveway-scraping front splitter and massive rear wing.
The lightweight forged rims are a half-inch wider at both ends and an inch bigger at the rear, the wheels now measuring 19 x 9.5-inch at the front and 20 x 10.5-inch out back, wrapped in trick Michelin Pilot Sport Cup 2 rubber 10mm wider front (265mm) and back (285mm).
Under the bonnet is where the most significant change has taken place, however, with the M4 GTS debuting BMW's water injection system.
Water is pumped from a five-litre tank in the boot and then sprayed as a fine mist into the intake plenum, which has the effect of reducing inlet temperatures, in turn allowing more boost and compression to be run, increasing power.
BMW is keeping mum on any figures, but word is that around 350kW/600Nm is well within the realms of possibility.
Of course, extreme care must be taken, as should the water not be evaporated sufficiently, it will enter the combustion chamber with potentially catastrophic results, however the system has been tested in the M4 BMW uses as a MotoGP safety car.
We'll bring you more news if, or should we say when, the GTS Concept becomes a production reality.