Congestion charge means that it will cost more to cross the toll point in Oslo during rush-hour. This is known as rush-hour fee.
Environmental differentiation rates means that those who pollute the most also pay the most at the toll point. In rate group 1, the set rates are divided into el-car, gasoline/hybrid and diesel. In rate group 2, the set rates are divided into Euro VI-standard, Euro V or older.
If you are unsure about your vehicles environment class, you can check this by finding your vehicle in Vehicle-information on Statens vegvesen webpage.
Time and environmental differentiation rates will be introduced at the toll point in Oslo on October 1. 2017.