If the roaster is able to…
If the roaster is able to get off the ground, it will be for very short bursts, maybe one or two seconds. And that will be with hundreds of pounds of extra weight. There's a great video on YouTube titled "Elon musks- Flying Car.. BUSTED!!" that explains the actual physics of getting a car to fly using cold air thrusters.
This will at best be a novelty, not a revolution in automotive technology.