2019 CT6 debuts Cadillac-exclusive twin-turbo 4.2-liter V-8 by deeperkins | Mar 21, 2018 | Uncategorized Cadillac, for the first time in 26 years, will have an exclusive engine — a 4.2-liter twin-turbo V-8, making good on a 2016 promise by Cadillac President Johan de Nysschen. Source: Auto Feed