How can I claim depreciation for a business use car I sold at a loss when I did not claim annual depreciation?

Depreciation adjustment when you used the standard mileage rate.

If you used the standard mileage rate for the business use of your car, depreciation was included in that rate.

The rate of depreciation that was allowed in the standard mileage rate is shown in the Rate of Depreciation Allowed in Standard Mileage Rate table,

You must reduce your basis in your car (but not below zero) by the amount of this depreciation.

Rate of Depreciation Allowed in Standard Mileage Rate

Year(s)                     Depreciation Rate per Mile

2019                                  $0.26

2017–2018                          0.25

2015–2016                          0.24

2014                                    0.22

IRS Publication 463