Cadillac has put the development of diesel engines on hold, as the wider industry pushes toward hybrid and pure-electric vehicles.
"Going forward, we will focus on electrification," he told the industry journal.
The report says Cadillac was caught unawares by the Volkswagen diesel scandal in 2015, but executives felt they were too far along the development path to abandon ship. The sale of Opel last year also hit Cadillac's diesel program hard, given the two brands were collaborating.
Both four- and six-cylinder engines were reportedly being developed. Carlisle didn't write the fuel off altogether, suggesting it'll still play a role going forward – especially in large cars, SUVs and pickup trucks.
Central to the desire to push into diesel technology was the drive to conquer Europe. The compact XT4 SUV was meant to offer a diesel variant by 2020, but there's no longer a guarantee that'll happen.
The range-topping CT6 is offered with a plug-in hybrid powertrain at the moment, pairing a 2.0-litre turbocharged petrol engine with an electric motor for 50km of battery-only driving.
That's the same approach taken by Volvo with its T8 Twin Engine hybrid setup. It's offered on models ranging from the V60 to the XC90, and is designed to deliver big-engine performance with small-engine economy.
Porsche has dropped the diesel Panamera in favour of a plug-in hybrid, while 48V mild-hybrid technology is allowing brands like Audi and Mercedes-Benz to extract better-than-ever numbers from their petrol-powered cars.