Gasoline prices will continue to decline through the summer because of falling crude oil prices and optimistic expectations for the war in Iraq, the U.S. Department of Energy said, according to the Detroit News. The department's summer energy forecast said gasoline prices would likely average $1.56 a gallon during the vacation driving season, a substantially more optimistic forecast than was issued a month ago. Then, the department expected motorists to pay more than $1.70 a gallon during the summer. The report, issued April 8 by DOE's Energy Information Administration, cautioned that prices are likely to vary widely in different parts of the country. It said gasoline prices in California, for example, are expected to be about 50 cents a gallon higher than the national average. Automakers, before the war in Iraq, were concerned that consistently high gas prices might hurt sales of SUVs and light trucks. Early year sales figures showed, however, that sales of lighter vehicles were up from 2002, according to the Detroit News.