I've managed to catch the red one from Jomtien beach a couple of times and was very impressed; cool and comfortable ride at resonable speed for 20Bt. I got a timetable form the driver. They run evry 5-20mins during the daytime and will stop any where you want on the route, not just the official stops. Not worth waiting for as no specific times, so you could end up waiting 20 mins, but a treat if it draws up at when you need to go back form the beach.