But it was a completely different story in the Northern Territory, where new vehicle sales rose by 10.6 per cent.
In Victoria, stage 4 restrictions hit hard, with new car sales plunging by 57.7 per cent.
Meanwhile, Federal Chamber of Automotive Industries figures show new car sales were down 21.8 per cent in September compared to the same month last year.
According to data analytics firm Datium Insights, used motor vehicle prices rose by 4.4 per cent last week after increasing by 2.1 per cent in the previous week, and stock remains considerably low.
The rolling annual total of new car sales last month was down 17.3 per cent on the year and the lowest annual total in 17 years.