Singapore drivers may soon be able to fill ‘er up with hydrogen by 2004, following a letter of intent signed yesterday by BP to build hydrogen-refueling stations in the island nation. The letter is similar to one signed in May by DaimlerChrysler promising to develop hydrogen-powered cars for the Singapore market. BP plans to start small, with one or two hydrogen pumps to be added to existing gas stations by 2003, a year before the cars themselves hit the roads. The pumps will serve around 15 cars and cost between $500,000 and $1.5 million to build. BP is optimistic about the project and said the steep prices will drop as the cars become more popular and more stations are built: “We think that in 20 years the internal combustion engine could be obsolete,” said Koh Kim Wah, president of BP Singapore.