Here is a handy tool that can automatically log your mileage. The Mileage Ace GPS Mileage Tracker comes with WiFi. Simply install it in your car, and you are done. The device logs your trip without you having to break a sweat. It has enough memory to hold years of driving.
You will be able to view date/time, address, date, trip duration, driven path, and other relevant data points. You can find out more about it here.