For the year 2013, it is still 14 cents a mile for charity miles.
(Driven in service of charitable organizations)
This is the only mileage allowance not to change for the year 2013.
Even though it is a small amount of money it adds up and you should take advantage of every deduction that you can.
Miles have to be recorded at the time that they are driven.
(Not while driving the car though)
You should print the free mileage log on this site.
The Internal Revenue Service can be very specific about accurate record keeping.
The IRS will not let you guesstimate.
As an example, if you drive your car for a charity 100 miles a week you should log those miles into your mileage log after each trip is finished and the miles are on your odometer. That is the best way to avoid and error.
If you use medical mileage at the rate listed for that purpose then you should also write the miles used right after the trip is finished to avoid any guesstimation.
After a year of doing this every week, it adds up. It doesn't seem like much at first, but when you add it all up it pays off.
Again use the mileage log.