When a Vehicle is fully depreciated and the client still uses it for business
can the standard mileage now be used. Thanking you in advance.
Yep. That is one of the great things about the Standard Mileage Rate ... you can keep using depreciation (built in) even when the Basis is zero. It is especially nice for high-mileage businesses.
Yes, any gain due to the depreciation would be recaptured.
But again, you can keep claiming the Standard Mileage Rate even when the Basis of the vehicle is zero. So that is effectively 'free' depreciation.