I have the P3 with glass windshield, hard roof, hard back panel, and soft doors. I live in Illinois and it hasn't got real cold here yet but I put a Mr. buddy golf cart heater in the cupholder of mine and it has kept the cab fairly warm with temperatures in the 20s. When driving down the road the shifter knob area is where I feel the most cold air coming in. If I can figure out how to cover that up better that little heater would do an excellent job.