Ha, I may be there in May. Last May, we were in Perth and we drove down from the city all the way to Albany.  Enjoyed ourselves tremendously.  A few things to note though:

Speed limits are to be obeyed religiously.  I remembered receiving a speeding ticket 3 weeks after we got back from our honeymoon and I believed we were caught while trying to find our way out of some forest as it was getting dark.  Even 5km out of the speed limit may get you a ticket - a relative got one while coming down a slope!

The other thing to note is, driving in the countryside at night.  You can find dead kangaroos and wallabies on the highways so avoid travelling in the night if you can help it.  We try to end our driving before it gets dark.  Since you are planning to go mid-June, I reckon, it will be dark by 5pm.

Get a higher CC car.  We rented the Ford Falcon, a 4000 CC car and you can't feel the speed even when you are going at 110km/h.  Unless you are going with your family, you can consider getting the Toyota Previa but they call it Tarago.  Try to rent from the bigger companies like Hertz or Avis or even Budget.  They have booths at the airport where you can pick up the car straight away and drive off to whereever you are heading.  Their excess is pretty high so make sure you get a travel insurance that also covers for excess.  All we did was to buy the difference.  Talking about insurance, this is a must in Australia as medical fees are high.  I was told by my relative that the ambulance will cost you $400 per trip.

Great Ocean Road is a beautiful place but it will take about 4 hours to get there from Melbourne city.  By which time you will be exhausted so do stay overnight before making your way back.  If you are taking the coastal road which is definitely more scenic be prepared for a meandering one.  This means it will slow down your travelling time. 

Don't forget to stock up on fruits and snacks to munch on.  We usually prepare some sandwiches, fruits, potato chips, chewing gums (those are yummy, especially the Wrigley's)juice and munchies in the car just in case our travel to the next destination takes longer than expected.  During winter, we tend to feel hungrier faster so these snacks help keeps temper in check.  A hungry person is an angry person especially in winter!

Hope you find these info useful.  Oh yes, before I forget, the petrol price goes up the further you are from town so top up your tank in the city before heading for the suburbs and pump along the way if you are going to the swa teng.  And don't forget your Ipod and driver's license!

Sometimes....

bomos,,,, tangkis,,,,and monks,,,,

also can cure sickness.....you know...

hehehe....!!!!