Long before Volkswagen emissions scandal spelled bad times for diesel, U.S. consumption of the fuel was bafflingly weak. Despite surprisingly robust economic growth, rising truck cargo, and pump prices that fell to parity with gasoline for the first time in six years, U.S. diesel use rose by only 0.2 percent in the first seven months of the year. That marked a sharp contrast with gasoline demand, which rose nearly 3 percent at the fastest clip since the 1990s, according to Energy Information Administration (EIA) data. Analysts and traders see several factors at play: lower traffic on diesel-powered railroads due to reduced coal and oil shipments; an economy increasingly tilted to services rather than heavy industry; and the baseline effect from unusually strong heating fuel […]