While Montrealers will be lining up for City and Colour's sold-out show at St. Denis Theatre next week on June 3, unbeknownst to them, the real treat may be opening act, Sleepercar. Smooth and sultry, the six-member band from El Paso, Texas, is a fresh taste of Americana. Their debut album 'West Texas' has a real country twang with a rock and roll vibe reminiscent of Bob Dylan, Blue Rodeo and Tom Petty. Go to www.myspace.com and listen to A Broken Promise. I promise you'll want to listen to it again and again and again…