It's not available. I doubt there was enough demand. Most M5 owners like to have direct control of the throttle. I know I do. I have never used the cruise control feature, forget about active cruise.
2014 ///M5 Individual Frozen Grey, Silverstone Full Merino, Piano Black, Exec Pkg, Drivers assistance plus, LED Pkg, Bang and Olufsen, 20" 343M Forged Alloy Wheels
Countermeasures: Bel StiR+, Laser Interceptor Quad HP, Zaon MRX
Upgrades: Eisenmann Sport with M Performance Carbon tips, Dinan anti-roll bars