who owns the vehicle, you or S-Corp if you I would recommend reimbursement checks. If S-Corp here's what the IRS says. for personal mileage, the cost (can use standard mileage rate) must be added to your W-2 along with gross up for FICA and Medicare taxes. you can then deduct all vehicle cost on S-Corp. Alternately to avoid payroll issues you can reimburse for your personal use. contemporaneous evidence of mileage regardless of who owns vehicle must be kept. failure can result in a substantial disallowance if audited. Don't forget you must tale a salary.
In addition if you have health insurance - two things. if the policy is in the name of the corp, then you must add it to your w-2 taxable wages (no fica or medicare taxes) the S-Corp gets the deduction as part of your wages. On your 1040 you then get a deduction for the SE Health insurance. IRS notice 2008-1, failure to do this requires that the corp not take the deduction for your health insurance and no deduction of your personal return. if the policy is in your name, the IRS requires that the S-Corp reimburse you. then you proceed as above as if policy in name of corp.
it is advisable to use a pro the first year. they can guide you things that you may not be aware of that can affect both you and corp.
