The 2006 Buick Lucerne is available as a 4-door, 5-seat sedan. Starting at $25,265, the 2006 Buick Lucerne CX is powered by a 3.8L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 19-mpg in the city and 28-mpg on the highway. The top of the line 2006BuickLucerneCXS , priced at $ 34,265 , is powered by a 4.6L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 17-mpg in the city and 25-mpg on the highway.