You can use “Data sense” to save data, while browsing with Internet explorer, if you are already on Windows phone 8.1. You can go to Internet explorer—–>settings and chose how the Data sense handles your data savings.
Now, Microsoft has released a new app, which can tell you how much data you have saved with help of “Data sense” while browsing. This app is known as “IE data savings” and can be installed from here.
You can see usage for Today, this week, this month and even last 6 months. It also shows you data savings history in a neat graph.