If your car has the 8L90 A8 automatic transmission then AFM (Active Fuel Management, V4 Mode) is active in all driving modes, Eco, Tour, Sport and Track unless you're in manual mode (paddle shifting), using an AFM disabler (Range Device) or the ECU has been "tuned" to eliminate AFM. If your car has the 7-speed Tremec TR-6070 manual transmission then AFM is only active in Eco mode. All other driving modes do not activate AFM.
Hope this helps
Ross