It seems like you're asking about the final stage of building a CO2 car, but there's no such thing as a "CO2 car". CO2 is a gas, not a material used to build cars.

Perhaps you are thinking of:

* Cars powered by CO2 emissions: These don't exist. Cars need a source of energy, and CO2 isn't a fuel.

* Cars with low CO2 emissions: This is a broad category. The final stages would depend on the specific technology, but generally include things like:

* Final assembly: Putting all the parts together, including the engine, transmission, body panels, etc.

* Testing and quality control: Making sure the car meets safety and performance standards.

* Finishing touches: Applying paint, adding decals, and installing accessories.

Please clarify what you mean by "CO2 car" so I can provide a more specific answer.