The 2008 Hummer H3 SUV is available as a 4-door, 5-seat sport utility. Starting at $39,560, the 2008 Hummer H3 SUV Alpha is powered by a 5.3L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 13-mpg in the city and 16-mpg on the highway. The top of the line 2008HummerH3 SUVBase , priced at $ 30,995 , is powered by a 3.7L , 5 - cylinder engine mated to a manual transmission that returns an EPA estimated 13-mpg in the city and 18-mpg on the highway.