The 2005 Buick LaCrosse is available as a 4-door, 5-seat sedan. Starting at $22,835, the 2005 Buick LaCrosse CX is powered by a 3.8L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 29-mpg on the highway. The top of the line 2005BuickLaCrosseCXS , priced at $ 28,335 , is powered by a 3.6L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 19-mpg in the city and 27-mpg on the highway.