The 2012 GMC Sierra 1500 Hybrid is available as a 4-door, 5-seat regular side. Starting at $40,010, the 2012 GMC Sierra 1500 Hybrid 3HA 4x2 is powered by a 6.0L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 23-mpg on the highway. The top of the line 2012GMCSierra 1500 Hybrid3HB 4x4 , priced at $ 49,990 , is powered by a 6.0L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 23-mpg on the highway.