I am not an accountant, but I was never able to deduct car expenses while having an s corp. Does the s corp own the car? I had considered buying a heavier truck/suv when one could deduct the whole cost in 1 year if it was primarily for business use and had over 6K pounds towing capacity. I chose not to do so, because I basically drove old cars. I don't know if the larger vehicle deduction is still available.
Several years ago my accountant told me the s corp could pay for mileage, but then I would have to add that onto my 1040 as income. It was a wash, so I just stopped keeping track of mileage, and stopped wasting any energy on this issue.
"Let us endeavor, so to live, that when we die, even the undertaker will be sorry." Mark Twain