The U.S. economy continues to perform like a Ferrari with a balky engine: stretches of strong performance on the highway, followed by stints in the garage for repairs. Economic growth overall is steady but slow. In May, the United States recorded the 75th consecutive month of job gains, the most ever, and the unemployment rate is low. Yet productivity is not growing, and wages for many workers remain stagnant. Moreover, the economies of oil-dependent states are struggling because of low oil prices. Then, in late June, came Brexit. The British vote to withdraw from the European Union roiled global stock markets, and some economists warned the turmoil could drag the U.S. economy down. But others expect the economy to grow modestly in the months ahead.