For those self employed needing to properly document their mileage without IRS Audits, there are a few reputable companies that are in business and manage for you:
This makes the assumption that a person would use their vehicle for 100% business - which for the most part won't be the case. As required in Publication 463 - "You cannot deduct amounts you approximate and estimate." They will probably need a mileage logger or a log book to document those personal or commute miles, business purpose and distance, etc. before they can make the claim. Since the majority of us fall under the self employed, a business vehicle travels at least 20,000 business miles per year and that equates to over $10,000 in deductions if used with personal/commute/charitable/medical purposes.
The deduction can be even greater if there are more business miles, but nonetheless both methods need to be verified with your CPA or tax preparer to maximize your deductions as it pertains to your business.
www.CRSinc.com
www.runzheimer.com
www.mileagelogger.com