If you use your car for work and want to claim some of the expenses in your personal tax return, you choose one of two methods, being:

1. Logbook method - To use this method you need to keep a logbook for a 12-week period.  Just pop down to your local newsagent and buy a logbook and follow the rules set out therein.
2. Cents per km method - To use this method you can claim up to 5,000k p.a. on a cents/km basis.  It is important to keep a record of what the travel was for e.g. 12 trips p.a. to bank x 30km return trip

Tip: the biggest mistake individuals make is claiming home to work and back again.  Unless you meet one of the specific criteria set out here, then you cannot claim home to work and vice-versa as this is deemed to be personal.

The ATO has recently sent out an update on claiming car expenses - ensure you are complying read more here.