My guess would be that $0 would not be the correct amount if you had actually sold the vehicle.
Does your 2021 Federal 1040 tax return include an IRS form 4797? If so, you may have reported the disposal of the vehicle as a sale. Then the state software is also reporting the sale information on the state 4797 or equivalent form. What state are you referring to?
When reporting the vehicle sale / disposal, at the screen Do any of these apply to the SUV?, did you select Your percentage of business use of the vehicle varied over the years?
If you did not, you may be reporting the vehicle as sold and not disposed of.
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