That's true, but arbitrarily picking 30km for the car and 4 hours for the car is useless. The only reason they did it is so they can say it pollutes as much as

That's true, but arbitrarily picking 30km for the car and 4 hours for the car is useless. The only reason they did it is so they can say it pollutes as much as 1,000 cars. You'd need to look at average km driven per day and avg time used per day for the stove. You'll note that they are also comparing old, non EPA certified wood burning stoves with modern EPA certified cars.