Carbon emissions are not the only worry. Because of the chemicals added to plastic, burning it to make fuel creates a lot of nasty air pollution. Nobody in their right mind will propose a switch to cars fuelled by plastic waste.
However, it is instructive to examine the motives behind this unanimous conclusion. Much of the plastic waste that the Volvo 240 burns burns anyways. Not in cars but incinerators. That is the case for 44% of plastic waste in Europe. That plastic waste burns to produce electricity, which can then charge electric cars. How is that more sustainable than burning plastic on the roof of your car?
They also added that the process as depicted uses unoptimized (the “de-refiner”) and old (the car) technology, so the the concerns that the CO2 production is high should also be put in perspective