The 2007 GMC Sierra 1500 Classic is available as a 2-door, 3-seat regular side. Starting at $26,295, the 2007 GMC Sierra 1500 Classic SL 4x4 Regular Cab 8' Box is powered by a 4.8L, 8-cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 19-mpg on the highway. The top of the line 2007 GMC Sierra 1500 Classic SL2 Sport 4x4 Crew Cab, priced at $30,340, is powered by a 4.8L, 8-cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 19-mpg on the highway.