A recent case, and the ATO's stance in relation to it, indicates that it is prepared to take a hard line on travel expense claims in relation to travel allowances paid to employee truck drivers.

Even though there is an exception to the substantiation rules for these sorts of expenses, (i.e., in terms of keeping receipts, etc.), the ATO looks like it may still expect truck drivers to be able to back up how many nights they were away, what they ate and where, and how they calculated the amount claimed.  These sorts of claims are often quite large and have become a target for the ATO.