How 2 report imputed income from 1099-NEC form w/o listing it as a self-employed business. Company vehicle personal use, i quit b4 they added it to my taxable income.

Your employer is required to include this as part of your taxable wages on your W-2.  It's not to be reported on Form 1099-NEC so first I would request they correct it on their end.  

For this reason it is subject to FICA withholding. This means that you would also be required to pay your share of that tax.  You can accomplish this by adding Form 8919 to your return.  Use the steps below to include this form.

1. Federal Taxes > Wages and Income
2. Other Common Income > Enter 1099-NEC for the time being
3. On the next screen, just briefly describe your work (Personal use of company car)
4. Immediately after the 1099-NEC entry you'll see checkboxes, including "your employer reported on a 1099 but it should have been on a W2"
5. Also select 'I received a Form W-2 and this Form 1099-NEC but all the income reported on this Form 1099-NEC should have been included on y W-2...'
6. Your return will now include 8919 and your share of social security and medicare tax.

You need to also mail SS-8 now, independently of your tax return. You can wait for that response, or go ahead with the 8919 now. If the IRS agrees that you were an employee, your return will not need to be changed.  It may take a while to get the SS-8 response, so go ahead with the 8919. The IRS will contact your employer eventually for their share of the tax.