Retail sales in the U.S. increased in August by the most in six months, boosted by demand for automobiles along with higher gasoline prices that left consumers with less to spend on other goods. The 0.9 percent gain followed a revised 0.6 percent advance in July that was smaller than initially reported, the Commerce Department said today in Washington. The median forecast of 84 economists surveyed by Bloomberg called for an increase of 0.8 percent. Sales slowed at department stores, apparel retailers and electronics outlets.