Basically, if the vehicle is less than 100% business use, you'll find it absolutely impossible to prove the actual costs to operate the vehicle for the business use percentage. That's why you use the per-mile deduction. For 2019 the per-mile deduction is $0.58 per mile for business use. That per-mile deduction includes depreciation.
But I don't see why anyone gets concerned about vehicle depreciation. Chances are when you sell the car, what you get for it won't come anywhere even close to the adjusted cost basis. (what you paid for it, minus depreciation taken) So in the end, you don't pay any tax on the recaptured deprecation. Even after recapturing the depreciation, you'll still be disposing of the vehicle at a loss.
If it's a vehicle owned by the business, then the business can deduct the loss.
