A bit of basic chemisty:
Most of the mass of petrol consists of carbon atoms.
Some round figures: A liter of gasoline has a mass of roughly 700 g. roughly 80% of that is carbon, about 560 g.
An atom of carbon binds with oxygen to form CO2. 1 atom of carbon weighs 12 hours, an atom of oxygen 16 hours. (and there are two in CO2)
In short, with 12 g of carbon and 32 g of oxygen you make 48 g of CO2.
So with 560 g of carbon: 560 g x 48/12 = 2240 g CO2.
My first GTL on old petrol (without ethanol) did on average 23 km per liter so 2240 divided by 23 gives 97 g CO2 per km.
The GTL is the more economical with fuel consumption, slightly bigger engine and small (28mm) carburetor.
The other models have a small engine and bigger carburetor so more fuel consumption.
But after all that is way less than the more modern cars with "modern" bigger engines they produce more CO2 emmision and don't forget that by adding ethanol in fuel, fuel consumption rises and so more CO2 emissions per km.
But basicly I don't care about CO2 emmision. Last year on the German news there was an item that since the 1980 all German car brand manufactures made agreements about emmision, future emmision rates and how to interpret them so it would be salable to the governments and the masses, we call it cartel formation agreements. I didn't hear that news on the Dutch channels... it was kept quiet (censorship).
And don't think that electric cars are the solution, just let's calculate how much tera watts are needed just to keep all vehicles rolling, and I don't mention vessels, houses, factory's etc. etc. etc.
Clean solutions have been invented since the 70s and 80s, but all those techniques are kept silent, in the eyes of the oil sheiks the Bugatti veyron has to continue to drive and Dubai has to continue to grow.