Slideshow ( 2 images )

DETROIT (Reuters) - The growth of car-sharing services will erode traditional manufacturers’ vehicle sales and revenues through 2021, but will not be nearly as disruptive as the rise of self-driving cars later in the decade, a study forecasts.

The evolution of car sharing services, such as those provided by Avis Budget Group's CAR.O Zipcar and Daimler AG's DAIGn.DE Car2Go, could trim global vehicle sales by 550,000 in 2021 and cost manufacturers more than $8 billion in lost revenue, according to a survey released on Tuesday by Boston Consulting Group.

But car-sharing will have a far greater impact in Europe and the Asia-Pacific than in North America, the study predicts.

Automakers in North America are expected to lose about 52,000 sales a year to car-sharing customers in 2021, but that will be offset by sales of 44,000 vehicles a year to car-sharing fleets, for a net loss of only 8,000 vehicles at a cost of just over $500 million, BCG researchers said.

In addition, U.S. automakers such as Ford Motor Co F.N and General Motors Co GM.N are investing in car-sharing services in several markets to supplement individual vehicle ownership.

In the longer run, according to the study, “autonomous vehicles will have a much greater impact on new-car sales than car-sharing will,” but not until 2027.

The study did not account for the short-term impact of ride- hailing services such as Uber and Lyft. But it noted that the arrival of self-driving vehicles in the late 2020s will trigger the convergence of car-sharing and ride-hailing.

Car-sharing will not be “a true game changer,” the study concluded, but self-driving cars “will change the game, erasing the distinction” between car-sharing and ride-hailing while providing users with “a significant edge in the total cost of ownership.”