I don't live in the snow, but I've been playing with all the other modes in my Trailhawk.
When the Renegade is in Auto it will automatically change between FWD and 4WD without any indication. I haven't noticed if the 4WD Lock light comes on when in Auto Mode. Even in the dirt and soft sand. The 4WD Lock light only comes on when I press the button for 4WD Lock. Then the Renegade stays in 4WD mode. I don't know the percentage from front to back and don't want to look it up right now. Each mode will have a different ratio of power to front/rear.
In most cases on the street the Renegade would mostly be in FWD mode. Acceleration and cornering might activate the 4WD, but I not sure because there is no indication of when the car switches. The surface of the street will effect the Auto to change from FWD to 4WD in most cases. Rain, snow, or dirt. As one tire loses traction, the power will go to the other tires to assist.
The Renegade does great in Auto Mode for what I've been testing it in. But I notice that Sand Mode, does better in sand than Auto Mode. The torque feels different and the engine revs sound different when using both modes in the sand.
Any hills I can climb in Auto Mode can easily be fixed with Rock Mode and 4 Low engaged.
I don't get enough mud and snow to compare those to Auto Mode.
As soon as I leave the pavement for dirt, I leave it in Auto Mode and turn on the 4WD Lock. I'm sure the Renegade can handle a good part of the trails I drive in FWD but I rather have the insurance knowing that it's always in 4WD. I get the added traction and I know its consistent. Instead of not knowing if/when the Renegade is switching between FWD and 4WD in Auto Mode when I'm on the trails.
I do the same in heavy rain. I don't leave it in Auto Mode. I engage the 4WD mode. I'm sure the Auto Mode system is very capable in switching between the 2 and I've driven FWD cars in the dirt and heavy rain with no issues. But knowing that I have the 4WD engaged and having the extra traction that it offers give me the satisfaction of using a feature that I have access to. The FWD in Auto Mode is suppose to help increase you MPG when 4WD isn't always necessary.
Or I can be totally wrong. This is just the way I see it and how I use it.