You can use any of the car valuation resources that are available to figure the fair market value FMV such as; Edmunds, NADA, Kelley Blue Book. You will want to figure the FMV of the car at the time you started using it for business purposes. For example, if you started using the vehicles in 2018 you will want to use reference information that was published in 2018.
[Edited 03/11/2020 | 10:46 am PDT]
