The only thing I've ever seen on determining straight line depreciation for a vehicle, "seems" to assume that vehicle was 100% business use, and it's not even on an IRS website. So I can't validate the accuracy of it. It's at https://smallbusiness.chron.com/depreciate-company-car-53368.html and make sure you read the entire article; not just the part related to straight line depreciation for vehicles.
