However the cost of spare parts has risen by the same amount and repairs and maintenance have risen by 11 per cent.
The Australian Competition and Consumer Commission wants to know why this has happened, and just whether car dealers are milking the aftermarket services for their own wallets as opposed to looking after consumers.
Australia has plenty of choice on what new car you may buy, but once you have acquired the vehicle you may be denied choices as to when and how to service them.
The regulator has just launched a year-long market study into the sector which will also consider whether we need a specific lemon law to cover car purchases.
The US, China and Singapore have laws which say if a new car has the stated faults then it is officially a lemon, which then triggers rights over the car sales team.
ACCC chief Rod Sims is not in favour of such a law in Australia because he thinks the rights of consumers are well covered by existing Australian consumer law.
But he has an open mind on the issue and is willing to test his theory in the market study.
Cars are the most commonly-recalled consumer goods for a long list of safety defaults. Last year there were 182 recalls, against 169 the previous year.
Then there is the issue with the fact that as soon as a car runs through its warranty period the problems seem to magically appear.
The study will also consider complaints that car dealers control access to the computer data on your car, which makes it harder to get work done by rival practitioners.
The forthcoming Productivity Commission report on data will recommend consumers win control of their personal data, which will cover everything from banking details to car mechanics.
Over the last five years the price of new cars has fallen by seven per cent.