The BMW M4 GTS is, according to BMW, the fastest series production car it has ever produced. And yes water sprayed into the intake to further cool the compressed air after the intercooler. The water evaporates to prevent knocking or damaging the engine. You will need to refill it from time to time.
The M4 GTS boasts a 0-62mph time of 3.8 seconds, 493 bhp and a water-injection system taken from the M4 Moto GP safety car. evo’s Hunter Skipworth explains the car in-depth here.