On January 1, write down your odometer reading on all the vehicles you use for business. Each time you drive anywhere for business, make a note of which car you're using, where you're going-including address and distance-as well as the business purpose of the trip. If you don't, you could be audited. The IRS is cracking down on vehicle deductions for taxpayers who have no records. OH -- and just so you know, the people who keep mileage logs often find that their business mileage is much higher than they originally thought.