The 2006 Honda Ridgeline is available as a 4-door, 5-seat regular side. Starting at $27,700, the 2006 Honda Ridgeline RT is powered by a 3.5L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 21-mpg on the highway. The top of the line 2006HondaRidgelineRTS , priced at $ 30,075 , is powered by a 3.5L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 21-mpg on the highway.