The 2006 Nissan Frontier is available as a 4-door, 4-seat regular side. Starting at $22,650, the 2006 Nissan Frontier 4x2 King Cab 6' Box is powered by a 4.0L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 20-mpg on the highway. The top of the line 2006NissanFrontierSE (A5) 4x4 Crew Cab , priced at $ 24,700 , is powered by a 4.0L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 20-mpg on the highway.