OSLO—The rise of the electric vehicle may be working to chip away at emissions here in oil-rich Norway, but it is creating an unexpected headache for some of the most important people in the nation's big city—bus drivers.

In the capital, Oslo, sales of electric vehicles have ballooned as well-heeled Norwegians take advantage of generous government incentives aimed at juicing sales of cars that run on batteries. Incentives include a number of tax breaks, free car-charging stations in municipal parking lots and exemptions from...