Sweden’s fuel suppliers are questioning the value of a new ordinance requiring them to provide motorists with greenhouse gas emissions information at the pump, beginning in 2020.

Under the new rules, gas stations will be required to provide information detailing the overall climate impact of the fuel they sell, as well as the origin of the fuel and the raw materials it contains. The rules will be mandatory for suppliers that put more than 1,500 cubic meters of liquid fuel (396,258 gallons) or 1,000,000 cubic meters of gaseous fuel (37,000,000 megajoules) on the market annually.

The requirement is...