BERLIN—In a European economy marked by terrorist attacks, the Brexit vote in the United Kingdom, political uncertainty amid a rise of right-wing populist parties, and volatile currencies, Europe’s auto makers have surprisingly little to complain about.

By this time of year, European new car sales were supposed to be sinking fast as growth was expected to slip from around 9% at midyear to an anticipated 4% to 5% for all of 2016.

But after dipping in July in the wake of the British vote to leave the European Union, ending a 34-month growth streak, new car registrations came surging back 10% higher in August from a year ago to push new car sales 8% higher for the first eight months of the year, according to the Association of European Automotive Manufacturers.

Now, as the biennial Paris Auto Show prepares to open its doors this coming Saturday, analysts and industry executives are wondering how long the good times can keep rolling. The show runs until Oct. 16.

Mark Fields, chief executive of Ford Motor Co. , which has struggled for years to make any profit in Europe, told investors earlier this month that the U.S. auto maker expected the momentum to continue in Europe, but warned of future risks.

“We actually expect this year to be one of our best years ever in Europe,” he said according to a transcript of the event. “At the same time there is new risk with Brexit.”

Even if car sales remain robust, car makers are expecting to struggle with the impact of Brexit and falling consumer confidence, which has caused the British currency to weaken substantially against the euro and other major currencies.

Ford, for example, does a big share of its European business in the U.K., and so is heavily exposed to the British pound. When Ford released results for the three months to the end of June, the company said it suffered Brexit-related currency losses of $60 million and expected those losses to widen to $200 million by the end of the year and reach $500 million a year in 2017 and 2018.

“After two months now, we think it’s going to be more like $600 million next year, but we have already done a lot of scenario planning and we have a lot of experience in the U.K., especially with weak currency,” Jim Farley, Ford’s president for Europe, the Middle East and Africa, told investors at the event earlier this month.

The dip in European Union car sales in July, immediately after the Brexit vote, was a foreboding sign of how quickly Europe’s auto recovery could come to a screeching halt. In July, new car sales fell 1.4% as consumers across the 28-nation bloc refrained from making big purchases in the wake of the Brexit vote.

Reflecting cautious comments by many CEOs at the time, Carlos Tavares, chief executive of PSA Peugeot Citroën, said during a call with analysts after publication of second-quarter results in July that his company felt no immediate impact from the Brexit vote or the shock from the terrorist attacks in Paris. But he warned of a growing uncertainty about the future.

“What we don’t know, both you and me, is what may happen in the world,” he said, according to a transcript of the conference call. “Consumer confidence may be impacted by events, and very sad events, like those we have faced in the last weeks both in Germany and in France.”

In the wake of the strong August sales figures, Arndt Ellinghorst, an analyst at Evercore ISI, a London-based brokerage and research house, raised his estimate for European car sales for all of 2016 to 14.65 million vehicles, up from a previous forecast of 14.4 million.

But he also warned that Europe’s auto recovery could soon begin to sputter.

“While the European market remains buoyant, we continue to have reservations and see risk with respect to the remainder of [the year] and 2017 in the wake of the U.K.’s vote to leave the EU,” he wrote in a note to clients.

Longer term, European auto makers also face rising costs of meeting tougher requirements to lower greenhouse-gas emissions and to invest in new technology ranging from electric vehicles and self-driving cars to ride-hailing and car-sharing services. Andrew Bergbaum, managing director of consultancy AlixPartners, said in a recent study that in the coming years the auto industry “will face its biggest upheaval since before Henry Ford.”