Ford took a big step forward yesterday in the race to build more environmentally friendly vehicles, announcing that it will reduce smog-causing tailpipe emissions from its light trucks an average of 33% beginning in the 2000 model year. It will cost Ford about $100 per truck to use improved catalytic converters and engine controls, but the price increase will not be passed on to consumers. Enviros applauded the move, though Roland Hwang of the Union of Concerned Scientists pointed out that low-emission light trucks are still two to three times more polluting than low-emission cars. Ford also acknowledged that this new initiative won’t lower the average fuel economy of the company’s vehicles, which is the highest among major automakers.