Auto Depreciation of one vehicle on two separate schedule Cs....

Can you explain how to handle Auto Depreciation of one vehicle on two separate schedule Cs when one of the businesses has been using the vehicle (and depreciating it) for a number of years, and then I started a second company (running both businesses at the same time). How do I show the vehicle depreciation on the second (new) schedule C while I still have business use with the vehicle in the first (older) business? The newest business is consuming 75% of the vehicle, while the older Biz is at 15%, with 10% personal use.