6 months in Australia by road from Sydney. Which way first?

The replies below suggest going north to QLD. I didn't suggest that because

1- you said you'd travelled already mainly up the QLD coast and
2- You seemed to emphasise the southern and western states.

Yes, there's the FNQ inland, but Sept Oct, especially Oct in inland FNQ it gets bloody hot and humid and gets worse as the year progresses. Was in Palmer River gold country around Laura in Oct 2010 - 42 deg. Awful. Depending when you start your trip, if you went north, that's about the time you'll be there.

NSW south coast and southern states will be cool in Sept, but you bracketed your starting date Sept-Nov. In Nov it's glorious and as you go south those cool states will warm up. Feb-Mar is best for Tassie.

Though it's lovely, don't confine yourself to the coast - there are beautiful hinterland and inland Nat Parks to explore and plenty of free camping in some Nat Parks and all state forests. Just check for hunting in state forests and some Nat Parks - you and your GF probably don't want to mix it up with JD and Coke, guns and pig dogs, etc.

If you go to WA you could maybe make a bit of a circuit in NSW, SA and Vic - coastal on the way there, and once back from WA, do some inland stuff.Flinders Ranges (SA) are hot in summer but cool off in autumn and are spectacular with wonderful camping in the gorges.

Perhaps from there to Clare Valley wine region if you're interested,

Mt Remarkable NP (Mambray Ck campground, but there are others),

onto the Murray via minor roads and towns, find your own free camps, there are plenty (explore tracks off the road near creek and river crossings) eg Yanyarrie Creek north of Carrieton.

Explore some history along the Murray (both Vic and NSW sides) on the way to Mildura and Wentworth (confluence of Murray and Darling rivers),

then maybe Lake Mungo (two campgrounds - the back one is nice via a 70km loop, get the notes for interpretation and history and is relatively secluded),

Menindee Lakes, Broken Hill.

From Broken Hill consider Mutawintji NP, wonderful walks, aboriginal heritage (book a guide if you can)

and then outback NSW to White Cliffs (great drive, opals),

then various state forests, Nat Parks, free camps to civilisation.

Or do that circuit vice versa, but try to do it in springtime. A bit hot in summer, especially outback NSW - Broken Hill, Mutawintji, White Cliffs.

Cheers

If his starting Sep-November you'd want to head straight for the Flinders. After those months the Flinders is basically closed over the summer.
Personally I think it's the wrong time of the year to start the trip with the places you want to go to.
Better off starting April head South and work back up through the Flinders and then across to Perth by mid June and then up north.

All in 6 months???? Wouldnt have time to stop for anything. Took us a year to do that and still didnt see everything.

True Tom, You could do it in 3 years and still not see everything. Or 5 years. everything is relative.

Just trying to help the OP with the locations he asked about.

Everything is a compromise but with a few 1500km faster sections you could cover it well.

Agree 100%. In my posts above I assumed standard 2WD campervan, not lifted and hence the routes I suggested - as well as climate considerations.

I've done Sydney to Perth return on a 2 week road trip so I think you can safely fit it into 6 months. :-) I've been to The Flinders, Uluru and Darwin in January and it's very hot and uncomfortable (Darwin especially), but still worth the trip. I've seen most of Australia in little 1, 2-3 week trips, visiting the same places multiple times. I have my own business and there's not a hope in hell of even getting away for a month so I have to do it that way or not at all. I even drove from Sydney to the Birdsville Track ferry over a long weekend plus the friday just to ride on the ferry. I had a great time.
However, if I was you and had the luxury of 6 months, I would head south and follow the coast as much as possible until I reached Perth. On the way back, I'd just take the shortest route. Allow a week to easily drive back from Perth at around 600 kms per day, although 1000kms per day out there isn't hard.
If by some chance you don't reach Perth, then do it next time.

Its 5000kms to Broome....I'm a bit of a driving machine but averaging 100kph for 50 hours straight would be extremely tough and 2 days is only 48 hours. :-) I like your can do attitude though.

Its shorter by the Tanami - less than 4000.

I used to do some crazy drives by myself when I was younger - Cloncurry to Canberra in 24 hours, Mundrabilla to Canberra in 25 hours. Sadly, I keep falling asleep now.

In July two of us drove back from Yulara to Echuca in 25 hours. We detoured through the APY Lands were we spent some time exploring on foot. One slept for a couple of hours while the other pressed on. It was pretty easy really. I reckon we could get to Broome like that in less than 48 hours. Not Cape York though.