This can depend greatly on which side of Brisbane you live on and also what time of the day you leave and drive.
If you are on the Southside of Brisbane you can add another half an hour to an hour to your trip time and if you are on the Brisbane Northside like me, take about a half hour off.
The distance from the middle of Brisbane to the middle Bundaberg is about 365km.
So, the time taken to drive from Brisbane to Bundaberg is about 4 hours.
For me, and I go up there once every three months at the moment, it takes me around the 3 and a half hour mark when there is no road works, there is road works at the moment though and so it takes anywhere from 4 to 5 hours to get there.