https://climatekids.nasa.gov/review/carbon/gasoline.html

Using imperial units is always unfortunate, but when dealing with the typical unit of gasoline in the US, it's inevitable.

Not sure where you are getting your numbers, perhaps you're using a UK gallon or something?

Well, no, when dealing with the typical unit of gasoline in the US, Imperial units are irrelevant, and US Customary units are inevitable.

https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca...

Your error appears to be using a single significant figure for the density of gasoline, at 700. Other sources place it from 711 to 749 kg/m3.

Hopefully you will reconsider my comment being "not nice," since you started with one sig fig and ended with four, and then did not consider the two different meanings of ton. And on top of this all, this ignores all the upstream emissions to generate the gasoline, which is greater than the 15% which you said was "not nice."

still well short of a ton

However, I already told you that I was using a US ton, 2000 pounds, 907kg:

https://duckduckgo.com/?q=1+ton+in+kg

Additionally, you are not including the 3-6 pounds per gallon in upstream emissions for gasoline.

Let's recall that this all started from the phrase "about 100 gallons of gas convert to a ton of CO2" and that when you quotes, you omitted the "about" so that you could try to make your incorrect quibble relevant. So at this point I would like to call this a very "not nice scientifically" departure from anything relevant, but I'm all ears if you were going somewhere interesting with this.

That density seems to be on the low end; different formulations have different densities, and the sources I’ve found give somewhat different ranges, but the ranges given typically seems to be about 750±35 kg/m³.

19.64 - http://www.patagoniaalliance.org/wp-content/uploads/2014/08/...

20 - https://climatekids.nasa.gov/review/carbon/gasoline.html

20 - https://www.fueleconomy.gov/feg/contentincludes/co2_inc.htm

19.6 (converted from grams) - https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca...

“Just over 19” - https://epicenergyblog.com/2013/05/24/how-many-pounds-of-car...

The next hit isn’t about CO2 from burning Gas, but about the upstream emissions that go into producing gasoline, which it pegs at 3.3 to 6.7 per gallon - https://www.sierraclub.org/sierra/ask-mr-green/hey-mr-green-...

What sort of estimates are you getting?

Yes, “gasoline” is a family of related fuels of different densities and compositions, and it will also vary based on assumptions about how it is burned. Incomplete combustion will result in more “dirty” pollution and less CO2.