I flat-tow a 2017 Mini Cooper Countryman S
All4 AWD vehicle with the 6-speed manual transmission. The owner's manual and the factory both say it cannot be flat-towed.
They are both wrong.
I did a pretty deep dive into this system to learn how it works. I also consulted with some
real world Mini techs who specialize in repairing these cars. They all told me that there was no
mechanical reason why these cars could not be flat-towed. The Mini/BMW
legal department is the entity that says they cannot be flat-towed.
As 16ACE27 said, it depends on the type of AWD system your car has. The Mini has what is called a "Hang On" system. It is the simplest of all the various AWD systems used today. Many other vehicles also use this simple system design. The only active device in the system is an electromagnetic clutch that is "hung" on the rear differential. If that clutch has no power, it is disengaged. So just to be sure, I installed a switch under the hood to disconnect the battery when we tow.
So far I have flat-towed this car over 3,000 miles with not a moment's trouble.