Ford Motor Co., which has vowed to boost the fuel economy of its sport utility vehicles by 25 percent by 2005, has killed an effort to use an innovative starter-generator system to make a more fuel-efficient version of its best-selling Explorer SUV, according to Ford engineers and suppliers familiar with the program, the Wall Street Journal has reported. The move is aimed in part at conserving cash, according to the Journal, as America's No. 2 automaker confronts its worst cash-flow crisis since the early 1990s. Ford earlier this year announced plans to use so-called mild-hybrid technology to allow the Explorer to go 27 miles on a gallon of gasoline, compared with less than 20 miles per gallon for some conventional Explorers. But now, Ford has concluded the benefits of the integrated starter-generator technology are greater on smaller vehicles than the Explorer, according to people familiar with the program. Jon Harmon, a Ford spokesman, declined to comment on whether Ford has canceled the mild-hybrid Explorer project. Harmon did conceded that "a lot of things in [Ford's product] plans are under review" as part of the company's overall study of its North American strategy. Ford is still fully committed to meet the 25 percent SUV fuel economy pledge, according to Harmon.