What ingredient in a Coke cleans a cars windshield?

My cars windshield had an unbelievable amount of grease and dirt on it. The windshield washer cleaner did not touch the grease, it only smeared it from one place to another. My wife grabs and opens a can of Coca-Cola and pours the contents onto the windshield, while my wipers were on. I was shocked at what i was witnessing. The grease and dirt disappeared!! Question: What’s the magic ingredient in a can of Coca-Cola that makes grime disasppear off a cars windshield?