A few things to think about;
The Luxury Car Import Tax in Aust applies from ~$57,466.00 and is 33% (Note: there are differences for Fuel Efficient Cars - Whatever that is). http://www.ato.gov.au/content/downloads/Bus13288n3394072010.pdf And this doesn't include GST which I assume applies on top of the Luxury Car Tax. This is why most cars in most other countries are significantly cheaper.
The average annual salary in 1972 was approx $4,700!! (Average weekly wage * 52 weeks http://www.ausstats.abs.gov.au/ausstats/free.nsf/0/1DED1C423EF40AD9CA25751600102E95/$File/63020_JUN1972.pdf ) A new 240Z was priced in Oz at ~$5,200.00 http://www.drive.com.au/buy/market_value/details.aspx?nvic=WIG&make=DATSUN&model=240Z&variantseries=SPORTS:&year=1972&body=2D%20COUPE&pg=1 Which means it was more than a year’s salary, in fact 1.1 times average annual salary. Current annual salary is ~$67,000 http://www.abs.gov.au/ausstats/abs@.nsf/mf/6302.0 and a new 370Z sells for ~$68,000 RRP. Meaning, if you take out the increases in luxury car import tax over the years, car prices from the manufactures have actually come down relative to annual incomes. In other words, cars are cheaper than they were, except the government is taking a bigger slice of the pie (how unusual...)
NOTE: I realise this is simplistic view, but the general principles are correct. Especially when you consider the gains in efficiency the car manufacturers have achieved in the last 40 years.