The 1999 Buick Park Avenue is available as a 4-door, 5-seat sedan. Starting at $31,130, the 1999 Buick Park Avenue Base 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 1999BuickPark AvenueUltra GM BuyPower , priced at $ 36,125 , 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.