The 2008 Cadillac XLR is available as a 2-door, 2-seat convertible. Starting at $80,650, the 2008 Cadillac XLR Base is powered by a 4.6L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 24-mpg on the highway. The top of the line 2008CadillacXLRAlpine White Edition , priced at $ 81,855 , is powered by a 4.6L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 24-mpg on the highway.