1Spray inside of 4- to 5-quart slow cooker with cooking spray.
2Remove inner skin from ribs. Mix brown sugar, salt, pepper, liquid smoke and garlic; rub mixture into ribs. Cut ribs into 4-inch pieces. Layers ribs and onion in slow cooker. Pour cola over ribs.
3Cover and cook on low heat setting 8 to 9 hours or until tender. Remove ribs from slow cooker. Drain and discard liquid.
4Pour barbecue sauce into shallow bowl. Dip ribs into sauce. Place ribs in slow cooker. Pour any remaining sauce over ribs. Cover and cook on low heat setting 1 hour. Note: This recipe was tested in slow cookers with heating elements in the side and bottom of the cooker, not in cookers that stand only on a heated base. For slow cookers with just a heated base, follow the manufacturer’s directions for layering ingredients and choosing a temperature.