The diesel discount was supposed to end this week. Naturally, we extended it.

Three weeks ago I wrote about what I'm fairly sure is the most powerful piece of energy policy in Australia, a thing called the Fuel Tax Credits Scheme, which has survived for decades by the cunning strategy of having a name so boring that no human being has ever willingly said it out loud in public. In that piece I made what felt like a safe, faintly smug little observation: that whenever fuel politics gets tense in this country, we reach, almost as a nervous tic, for the one lever marked "make diesel cheaper." I did not expect to be proved right inside the month. I certainly didn't expect to be proved right by an announcement slipped out over a weekend, which is where governments quietly file the things they'd rather you stumbled across on your own.

Here is what happened. Back in late March, when diesel was sitting well over three dollars a litre in the cities and nudging toward three-fifty in the parts of the country where the next servo along is more of a rumour than a fact, and the Strait of Hormuz had effectively shut, the government halved the fuel excise for three months. Sensible enough. That cut was always going to end on 30 June. Everyone knew the date. It was written into the legislation, which is about as committed as a date gets.

And then, over the weekend, it didn't end. It tapered. From 1 July to 2 August, petrol and diesel keep a discount of 16 cents a litre, roughly half the original relief, before the full excise of 52.6 cents (which then nudges up again with its scheduled August indexation, because of course it does) comes back. The reason given, and I want to be fair because it's a perfectly decent reason, was to give everyone "a graduated return to normal settings," which is the sort of phrase that takes a $400 million decision and irons it completely flat. On Monday, national cabinet got the states to chip in their share, and the whole thing was done.

And the timing has a certain dark comedy to it. That very same week, the global oil price slid back below US$70 a barrel for the first time since early March, roughly where it had sat when the whole thing began. The emergency, in other words, was quietly unwinding itself at the exact moment we decided to extend the emergency measure.

Now, tucked inside that announcement was a second number, and this is the one I'd like you to hold on to, because almost nobody noticed it.

Trucks. Specifically, the Heavy Vehicle Road User Charge, which is the slice of fuel tax that big diesel trucks actually pay for the privilege of grinding up our roads. Normally it's 32.4 cents a litre. Since 1 April, it has been zero. Nothing at all. And because of the slightly baroque way the whole thing works — the government charges the trucks the tax, then hands most of it back to them as a credit, a sort of fiscal hokey-pokey where the money goes in and the money comes out — the practical effect was that for three months, the heaviest vehicles on the road, the ones that chew up the tarmac the most, paid essentially nothing toward fixing it. By design. I'm not outraged by this. I just think it's worth saying out loud, slowly, because when you do, it sounds a bit mental.

Now hold that next to what was happening down at the car yard.

In May, electric vehicles hit a record 19.9 per cent of the new car market. Not a fluke, either. The third record month in a row, climbing from 14.6 per cent in March to 16.4 in April, and more than double where it sat a year ago. The Tesla Model Y outsold every other vehicle in the country — petrol, diesel, ute, the lot — the first time in history an electric car has topped the Australian charts outright. Sales of petrol cars fell 30 per cent. Diesel fell 26.

There's no mystery about why, and to its credit the Electric Vehicle Council didn't pretend there was: cheaper models, the efficiency standard, and yes, the price of fuel, all of it in the mix, and the Council is honest enough to say so. But here's the part worth dwelling on. The price shock didn't make the electric car cheap to run. It was already cheaper to run. What the shock did was make people finally look, because the misery the electric option spares you from was suddenly on the news every night and on your fuel receipt every fortnight. The economics were sitting there the whole time. The crisis just switched the lights on.

So here's the part I keep chewing on.

The same government that, on one side of the building, is busily handing out charger grants and cheap loans for electric trucks and writing vehicle efficiency standards, is, on the other side of the same building — down the corridor, past the staff kitchen where someone is reheating fish like a lunatic — spending $400 million to soften the exact price signal that just drove electric cars to a fifth of the market. Not out of villainy. Out of an entirely human urge to stop people hurting at the bowser, which is a fine urge to have. But a spreadsheet doesn't have urges. A spreadsheet just adds up. And whatever anyone intended, the diesel column got propped up again, in the same month the electric column had the best result of its life.

I should be fair about the Road User Charge, because it's the obvious comeback and it's a good one. It isn't a diesel subsidy. It's a cost-recovery charge, the bit that's meant to cover the wear a forty-tonne truck inflicts on a road that a Corolla simply does not, and quietly pausing it during a price shock is cost-of-living relief, not some grand pro-diesel scheme. And here's the genuinely funny twist: electric trucks, right now, pay no road user charge whatsoever, which is a thumb on the scale pressing the other way, and one the motoring clubs keep warning can't go on forever. So the tax picture is, honestly, a muddle. But none of that changes the one thing a bloke running a fleet actually feels, which is that for three months the running cost of his diesel was being held down by the government, on purpose, and the running cost of the electric thing parked next to it was not.

I made a version of this argument three weeks ago, and a few people, reasonably, said it was a bit abstract. Two arms of one government pulling opposite ways, fine, lovely, but where does it actually bite? Well. This week it bit. And you can put a date on it. 1 July

The clearest place to see it is freight. When someone sits down to compare a diesel truck with an electric one, one of the wobbliest numbers in the whole sum is the running cost of the diesel. It's the figure that lurches around the most, and the most visibly. And it is precisely the figure the government keeps reaching in to steady, like a parent holding the back of a wobbling bike. Three months at zero road user charge. Now back in two careful little steps instead of one. Whatever else you call that, it is price stability, handed free of charge to the technology that's been around for a century, at the exact moment its rival started to look like the safer bet. Nobody's doing that for the electric side. There's no soothing taper when the price of electricity spikes. There's no emergency national cabinet about the demand curve for charger installers. The electric option carries every bit of its own volatility, alone, while the diesel option gets a government standing quietly behind it with a steadying hand.

And before anyone reaches for the obvious objection about scale: yes, $400 million for one month is real money, but it's loose change down the back of the couch next to the $10.8 billion the Fuel Tax Credits Scheme hands out every single year, crisis or no crisis, rain or shine. That was never the point. The point is that the diesel reflex is automatic. It fires by itself, every time, while the electric side stands politely in a queue waiting for a program to open.

Let me be clear, because last time some people thought I was arguing the opposite: I am not saying we should have yanked the relief away on 30 June and walked everyone into a wall. Do that and you flatten the farmers and the small operators and the regional families who don't have an electric option yet and were told this would ease off gently. The taper is kind. The taper is the right call. The taper is not the problem.

The problem is the story we keep telling ourselves about which of these two things is the temporary one. We treat the diesel discount as the emergency measure — the thing we do reluctantly, briefly, holding our nose, when the world wobbles. And we treat the electric transition as the calm, settled, long-term plan. This week is a quiet reminder that it might be the other way round. The discount is the reflex. It's the thing that always, somehow, gets extended. The transition is the thing that has to survive the reflex.

So if you run a fleet, here's what's worth holding on to. For the right runs — the high-utilisation, return-to-base, predictable ones — the electric sums already add up today, on economics alone, no crisis required. And where the comparison still looks closer than it should, where the electric truck lands almost-but-not-quite, it's worth knowing that one of the reasons was decided, quietly, last weekend. Even when the relief itself ends on 2 August, the instinct that produced it will still be there — hand hovering near the lever, waiting for the next time the world wobbles.

Andrew Giannasca is the founder of AJMG Solutions, an Australian advisory firm working with government and industry on transport electrification, heavy-freight decarbonisation and charging infrastructure. He was on the founding team at JOLT, one of Australia's first commercial public EV charging networks, which now operates in 5 countries.