depends on what part of sydney you are in, but you could go down the freeway to mossvale/ fitzroy falls and have a play around Meryla state forest. Its got a bit of everything, from small shallow creek crossings, to a good little Low range hill climb or some ruts. There are some great lookouts over the escarpments and you can drive from Mossvale through to the Fitzroy Falls (you actually drive meters from the actual falls) A great book to buy is the "Boiling Billy" book "4WD Tracks Close To Sydney" by Craig Lewis & Cathy Savage. In there you will find all sorts of great locations from lithgow "newnes/ glow worm tunnel to the south coast . well worth a few $ and will keep you busy fro a year or two.