Tesla's sales dropped for the fifth straight month in Britain, Germany and Italy in May, underscoring the challenges the electric vehicle-maker faces over CEO Elon Musk's politics and its model line-up.

Meanwhile, in Norway, Tesla sales were up an astonishing 213 percent year over year in May. One key difference: Norwegian buyers have begun receiving the refreshed Model Y, while the model will only start to be delivered in major countries such as Germany, Italy, France and Great Britain in June.

KBA said Tesla sold 1,210 cars in Germany in May, down 36.2% from year earlier, while the total number of newly registered electric vehicles increased by 44.9%, KBA added.