The 2006 Cadillac XLR is available as a 2-door, 2-seat convertible. Starting at $76,480, the 2006 Cadillac XLR Base 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. The top of the line 2006CadillacXLRStar Black Limited Edition , priced at $ 78,980 , 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.