Place pork loin roast in a large resealable plastic bag.
Combine cola, honey, Dijon mustard, minced onion, paprika, olive oil, minced garlic, and rosemary. Pour 2/3 of the mixture over the pork. Toss to coat and seal the bag. Marinate in the refrigerator for 4-6 hours.
Reserve remaining marinade for basting. See below for details.
Preheat grill to medium heat. Remove the pork roast from the bag—season roast with salt and black pepper.
Assemble loin on a rotisserie over an aluminum drip pan. Add 1/2 cup of water to the pan. Turn the rotisserie unit on and cook pork roast with the lid down.
Simmer reserved marinade over high heat for 1 minute, stirring often. Reduce heat to medium-low and continue simmer for 2-3 more minutes.
Remove the sauce from the heat, cool for 5 minutes, and baste the roast every 15 minutes until done.
Cook pork loin for 1 1/2 hours or until it reaches an internal temperature between 150 degrees F. Check multiple spots to confirm its doneness.
Once cooked, use heat-resistant gloves to remove the roast from the grill. Take apart the rotisserie rod and prongs, and slide pork loin off of the rod.
Place your rotisserie pork loin onto a cutting board and rest it for 10 minutes.
Carve into 1/2 inch thick slices. Serve with a side sauce or compound butter of your choosing.
Store your leftover pork loin roast in an airtight container in your refrigerator for 3-4 days. Reheat in a skillet for best results.