The 2006 Cadillac CTS is available as a 4-door, 5-seat sedan. Starting at $29,270, the 2006 Cadillac CTS Base w/1SA is powered by a 2.8L , 6 -cylinder engine mated to a manual transmission that returns an EPA estimated 17-mpg in the city and 27-mpg on the highway. The top of the line 2006CadillacCTSSport w/1SB , priced at $ 35,570 , is powered by a 3.6L , 6 - cylinder engine mated to a manual transmission that returns an EPA estimated 17-mpg in the city and 26-mpg on the highway.