Thats comically wrong. Human Resting metabolism is on the order of 20grams of CO2/hr.

See: https://www.sciencedirect.com/science/article/pii/S036013232...

As for a kilo of gas per 10 miles- see https://en.m.wikipedia.org/wiki/Gasoline - says 0.71-0.77g/mL, standard conversion table says 3.785L per gallon. (https://www.engineeringtoolbox.com/volume-units-converter-d_...), and finally- since we're comparing burning gas for a car vs using it in plastic: the figure of merit is petroleum usage, not greenhouse gas emission. Technically, plastic and gasoline aren't going to be 1:1. But that's not napkin math anymore unless you're a petroleum engineer/chemist.