Twice a day, the No. 158 commuter bus driven by Jack Scott makes its way between the Vancouver suburbs of Port Coquitlam and New Westminster. It would not be anything remarkable save for the fuel cell in the back - a potentially revolutionary cell that carries the hopes of advocates of cleaner air everywhere, to say nothing of the millions of dollars ofinvestment money ponied up by some of the world's biggest automakers. "There's no vibration, no transmission, so it's less jerky. It's a Cadillac of a bus," said Scott, an eight-year veteran of BC Transit who has been driving the fuel cell bus since the middle of last December. The experimental bus is one of three working in and around Vancouver, developed by Ballard Power Systems Inc. ,of Burnaby, a Vancouver suburb.