The 2007 GMC Sierra 1500 is available as a 2-door, 3-seat regular side. Starting at $32,155, the 2007 GMC Sierra 1500 SLE1 4x4 Crew Cab 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 2007GMCSierra 1500SLT 4x4 Extended Cab 6' Box , priced at $ 33,955 , is powered by a 5.3L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 20-mpg on the highway.