For a less complicated life, you should all immigrate to Victoria (the best state in Australia) where there are no inspections required other than a roadworthy certificate when you first register the car in your name, after that all you do is pay the annual registration and compulsory third party insurance (which is included in the registration fee) when the notice comes.
No bloody SORNs, V5s, MOTs or any of those other bureaucratic nightmares.
The RWC (roadworthy certificate) can be a problem but no so much if you find a friendly RWC tester.
You might think that without annual or regular inspections that we would have a higher accident rate, but when compared to the states that have annual inspections, we don't, so based on that regular inspections would appear to be a costly waste of time and effort.
Every year the VACC ( Victorian Automotive Chamber of Commerce ) pushes the government for annual inspections, of course the fact that they have a vested interest that would financially benefit their members has nothing to do with their concern!
And every year the motoring lobby including the ultra conservative and highly respected pillar of the establishment, the RACV (Royal Automobile Club of Victoria ) successfully opposes the VACC's push. Thus the balance of the universe is maintained!
When we were in Melbourne one Aussie guy that worked for us who lived in Boronia (Vic) used to take us water skiing some weekends to Lake Eildon, he was always moaning about the registration as his Holden pick-up (ute) boat trailer and boat as all had to be registered separately and all had their own registration number (number plate) he said it was Victoria's revenue collection.
Not sure if it's still like that now (we came back to the UK in 1998) but it looked strange to see a different number plates on the towing vehicle to the trailer and I could never understand why you would need a registration number on a boat!
Underbody corrosion is rife in the UK due to the rock salt that's put on the roads during winter, plus the very high humidity.
No annual check (MOT) for the first 3 years of date of first registration then annually after that. If we didn't have the MOT we would have a lot of very dangerous vehicles on our over populated roads which are in a very sad state at the moment.
I think the other reason for our MOT (controlled by the EU, now Euro 6 standard for 2014) is about reduction and compliance in exhaust gas emissions (part of the MOT check) The MOT is around £50 and takes about 45 minutes which will only cover the labour so no revenue to the government is collected, revenue is collected by an annual road tax which could be zero for an electric car and up to £500 for a high emission car (255g/km) there are 13 price bands between high and low. The other cost is annual car insurance where the minimum cover is 3rd party only.
As an example for the TF annually I pay around: £468
MOT £50
Road Tax £265 (194 g/km)
Fully comp insurance £153
Not sure how the costs compares with your F in Aus.
Newly registered diesel engined vehicles are now getting a pounding with Euro 6 and most will have a DPF (diesel particulate filter) fitted between the exhaust manifold and CAT. When conditions are correct from engine RPM, engine temperature and exhaust gas temperature the passive conditions in the DPF should vaporise the collected particles and the filter should self clean. If these conditions can't be met (only short journeys at low speeds) then an active process starts, a small amount of post fuel injection takes place (controlled by the engine ECU) to increase exhaust gas temperatures to help the burn off.
Engine manufactures all have their own variation and some even inject diesel into the DPF directly. Unfortunately this new system is not working very well for all engine manufactures and DPF's are getting blocked, as this starts to happen the EML will come on to let you know there is a problem (pressure build up in the exhaust system) and it may put the engine into limp mode so you can just get to the dealer; who may be able to clean the DPF or worst case a new DPF.
Brian.