You have to include more than just oil refining too:
- there's the CO2 emitted during manufacture of the vehicle and maintaining the vehicle
- the CO2 emitted to construct and maintain the roads the vehicle is used on (apparently this is about the same as the CO2 produced in making a car, per metre of road [1])
- since society is so massively oriented around vehicle use, you would probably need to apportion some significant amount of the CO2 emitted by the bureaucratic machine that allows for widespread vehicle use -- lawmakers, financiers, road engineers and regulators, police forces that enforce traffic codes -- this all costs a lot of energy and therefore carbon so it could be a non-negligible contribution
- to much lesser order, the CO2 you yourself emit in order to operate the vehicle and maybe the CO2 emitted in building your garage where you store the vehicle
The oil tankers that shuttle the oil around the world have very few or non-existent emissions controls on top of everything else. Global shipping is a race to the bottom where all the ships are flagged in the country with the least regulation and the owners hide from responsibility through a chain of shell companies.
- there's the CO2 emitted during manufacture of the vehicle and maintaining the vehicle
- the CO2 emitted to construct and maintain the roads the vehicle is used on (apparently this is about the same as the CO2 produced in making a car, per metre of road [1])
- since society is so massively oriented around vehicle use, you would probably need to apportion some significant amount of the CO2 emitted by the bureaucratic machine that allows for widespread vehicle use -- lawmakers, financiers, road engineers and regulators, police forces that enforce traffic codes -- this all costs a lot of energy and therefore carbon so it could be a non-negligible contribution
- to much lesser order, the CO2 you yourself emit in order to operate the vehicle and maybe the CO2 emitted in building your garage where you store the vehicle
[1] I believe I heard that in this kurzgesagt video: https://www.youtube.com/watch?v=yiw6_JakZFc