I receive 600.00 a month for my car allowance, I am in sales, I do not receive a 1099 or W2 , this money is paid separately on my expense report, do I have to include?

Are you a self-employed sales person who filed a Form 1040 Schedule C?

I am a W-2 Employee,

W-2

ok ,  I have no idea what plan they have?  I am not required to pay any money back, is that an accountable plan?

I suggest asking your employer if they have an accountable plan. Just because you are not required to pay money back doesn't mean it's an accountable plan. To be an accountable plan, your employer's reimbursement or allowance arrangement must include all three of the following rules:
You must have paid or incurred expenses that are deductible while performing services as an employee
You must adequately account to your employer for these expenses within a reasonable time period, and
You must return any excess reimbursement or allowance within a reasonable time period

If the car allowance is not on your W-2, you may have an accountable plan, and if you do, you do not need to include the car allowance on your tax return.

According to IRS "If your employer reimbursed you or gave you an advance or allowance for your employee business expenses that's treated as paid under an accountable plan, the payment shouldn't appear as income on your Form W-2.pdf, Wage and Tax Statement. You don't include the payment in your income, and you may not deduct any of the reimbursed amounts."

https://www.irs.gov/taxtopics/tc514