* Control Trac®: This was a part-time system. It engaged the rear wheels when slippage was detected in the front wheels. It wasn't a full-time AWD system like some competitors offered. It primarily improved traction in slippery conditions like snow or ice, but wasn't designed for constant use in all driving situations.
* Optional Full-Time AWD (in some higher trims): Some higher trim levels of the 2005 Mountaineer offered a more sophisticated full-time all-wheel drive system. This system continuously monitored wheel speed and transferred torque to the wheels with the most traction, providing better handling and stability in various conditions, not just when slippage was detected.
It's crucial to check the specific details on the vehicle's sticker or owner's manual to determine precisely which AWD system (Control Trac or full-time) a particular 2005 Mercury Mountaineer is equipped with.
