BMW 540i E39$8,000.
Audi A8 V8 D2
HSV Clubsport 15th Anniversary$6,500
A few words of advice before you go out a buy one of these cars though. The stretch of road in question is a 31 hour drive from Sydney and 26 hours from Melbourne, that's a commitment already. Secondly there are no local amenities once your past Alice Springs and importantly no petrol stations, so best bring a Tim Tam and a jerry can. Thirdly seriously consider if your bargain performance car is reliable enough to get there, do 250km/h without exploding and get you home again, these cars are good but some are pushing 20 years old. Lastly the road surface on the Stuart isn't flawless, it dips and undulates so mashing the go faster pedal isn't all you need to do, it will take concentration and skill to vmax your motor up the highway. With all that in mind though it's still hard to disagree that these 5 cars offer some serious oomph for very little dollar. All cars found on carsales.com.au