The 1999 Buick LeSabre is available as a 4-door, 5-seat sedan. Starting at $22,890, the 1999 Buick LeSabre Custom 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 30-mpg on the highway. The top of the line 1999BuickLeSabreLimited GM BuyPower , priced at $ 27,250 , 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 30-mpg on the highway.