The 2003 Buick Park Avenue is available as a 4-door, 5-seat sedan. Starting at $39,725, the 2003 Buick Park Avenue Ultra is powered by a 3.8L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 27-mpg on the highway. The top of the line 2003BuickPark AvenueBase , priced at $ 34,600 , 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.