The 2006 GMC Sierra 1500 Hybrid is available as a 4-door, 5-seat regular side. Starting at $26,205, the 2006 GMC Sierra 1500 Hybrid SLE1 4x2 is powered by a 5.3L, 8-cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 21-mpg on the highway. The top of the line 2006 GMC Sierra 1500 Hybrid SLE2 4x4, priced at $31,900, is powered by a 5.3L, 8-cylinder engine mated to an automatic transmission that returns an EPA estimated 17-mpg in the city and 19-mpg on the highway.