It seems that 1.4 L TSI engine is particularly susceptible to detonation damage from low octane fuel in Australia, have you been replacing pistons in these engines?
Iām mostly a ācoach mechanicā, @Nevada_545 
These 2 pictures are from one quite professional Russian engine rebuilder to which Iām subscribed at YouTube.
He reports that in his experience, it is very common for these engines to get damaged by low-octane gasoline, this type of damage is very common for VW 1.4 TSI.
Surprisingly, as he goes through the engine disassembly, he says that most of these engines do not even need to have cylinder bores to get machined beyond re-honing, and indeed this engine block did not have a single scar on the wall, while the engine pan had a totally terrible mess of broken rings and piston.
His repair is to get aftermarket forged pistons and in his experience they hold longer than originals.
Engine on these pictures has under 50K kilometers, so only tad bit over 30K miles.
Another thing to mention about late VW engines from watching his āautopsy videosā is that timing chain design is very succeptible to early failure from over-stretch, so his āpatientsā of VW descent come partially from detonation damage, but mostly from stretched/torn timing chains.
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Hi CSA, letās not bring ISIS into this. Thanks.
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This topic sure brings out folkās opinions, thatās for sure 
Even so, the discussion above is pretty informative too. For example, the comments that the manufacturerās motivation for ārequiringā premium in some of their cars might not be b/c lower-octane fuel would damage the engine, but could instead be an emissions or advertised power issue.
As far as the poster who recommends āget a real mechanicā, I expect most posters here would agree that if you have a car problem youāll likely get better results taking it to a good shop where they can actually inspect the situation, than asking anonymous people on the internet how to fix your car. Not saying the latter hasnāt value, but the former is more likely to actually get the car working again for your Monday AM commute.
I guess Iām not a real performance nut when it comes to buying family carsā¦ I mean we do have speed limit laws, traffic, pedestrians, etcetera. Itās cool to have a hi-performance car so one can boast or have folks envy it or burn a little rubber up to the speed limit, but ā¦
I donāt need to speed and donāt need extra attention to get my kicks. When I buy a car one of the first things I check is to make sure the thing is designed to run on 87 octane. Every one Iāve bought will more than keep up with traffic, give decent performance, and pretty good fuel economy.
Now, that said, having an extra sports car as a hobby car I have no problem with, but as a daily driver give me a regular gas burner.
I need to buy lots of premium gas like I need tap dance lessons.
CSA
P.S.
Sorry about that. I was just adding to comments about ridiculous lawsuits for Judge Judy to handle. I didnāt/donāt really understand why itās not appropriate (must be a PC thing? Iām not good at PC detection. It hasnāt existed most of my lifetime) Anyways, I respectfully withdraw my ISIS comments.
Manufacturers would prefer if all cars required premium fuel. Why? Better fuel mileage from higher compression engines. But they know some people wonāt buy their cars if premium fuel is required.
As to people buying expensive cars and not wanting to pay for premium gas. It is like someone spending $800 on a smart phone and then complaining that a productivity app is too expensive at $5.
Some of this conversation has been very educational as a non-car guy. I didnāt know about pre-ignition and that premium gas is less likely to have this problem and that you use premium gas with engines that run with higher compression. Good to know even it Iāll probably never own a car that needs premium.
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Never say never! You may eventually own a premium fuel car. The requirements for premium seem to keep expanding to more and more models in the quest for efficiency. 
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Well, I bought a new Subaru Impreza in December so Iām up for a new car in 2039. My old one would have lasted more than 20 years if it wasnāt for a hit-and-run 2 years ago that did some subtle damage.
Speaking of Subarus I spotted one a few days ago that I rarely see. A full size Outback sedan.
Many years ago myself and a friend tore apart his engine after he ran it hard while it was knockingā¦then stopped running.
Two of the 8 pistons had holes in them. If the owners manual says you need to use high-test, then I sure as hell would.
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Iāve seen at least one newspaper or e-zine article that predicted high octane gas only for new cars in the next ten years.
Have you ever used regular unleaded gasoline in your wifeās ES 350?
I always used regular in my ES300. Same engine as the V6 Camry (including compression ratio), premium was ārecommendedā, not required. I found no difference in power, mpgs, and never heard a knock.
Do engines still knock with too-low octane? Or do they adjust timing or whatever to eliminate knocking, and just accelerate a little slower?
If they knock, we old timers know to let up on the gas, or shift to a lower gear, or buy higher octane next time.
Pre-ignition causes a high levels of oxides of nitrogen, knock sensors are necessary on modern cars to prevent pre-ignition to meet emission control standards.
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ā¦ and knock sensors have been known to failā¦
And then the Check Engine light comes on.
Tester
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Of course, that is true, but it is also true that a whole lot of people drive around for years with their CEL lit up. My āfavoriteā query from several years ago was from a woman in Maine who drove some type of Suzuki, and her question was something along the lines ofā¦
The Check Engine Light on my car has been lit up for the past 16 years. What is wrong with my car?
I have replaced many knock sensors but no damaged pistons on engines equipped with knock sensors.
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