I would be inclined to save your money and stick with what you have got if it is doing the job, fuel in the outback is expensive anywhere you go and in some cases a lot more expensive for diesel.

All cars have problems, but you may be interested in reading about this blokes problems with his Kia on a recent around Oz trip, mainly with getting parts in a country town, but hey! I had trouble in Townsville with a Camry I had and Toyotal Townsville had to get the parts flown in from Melbourne, the first lot went astray and they had to order it in again......nice place to be stranded though, same as this bloke, Esperance a nice place too....

See his blog for Kia breakdown, keep going for later pages etc until he get it fixed to carry on....;

http://www.mytripjournal.com/travel-705539