Blaming private car ownership for greenhouse gases is at best misdirection. It reminds me a lot of the war on plastic straws.
Yes, obviously it contributes a lot.
However, commercial and industrial sources (especially power protection and industry) far outweigh private transportation (which on this graph is a part of the green wedge; which contains private and commercial transportation).
(Source: EPA, Total U.S. Greenhouse Gas Emissions by Economic Sector in 2021 https://www.epa.gov/system/files/images/2023-04/total-ghg-2023.png)