The 2020 Cadillac CT6 is available as a 4-door, 5-seat sedan. Starting at $58,995, the 2020 Cadillac CT6 3.6L Luxury is powered by a 3.6L , 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 2020CadillacCT64.2L Twin Turbo Platinum , priced at $ 96,495 , is powered by a 4.2L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 14-mpg in the city and 25-mpg on the highway.