How to Save Money on Petrol and Fuel Costs

Fuel is one of the largest regular expenses most New Zealand households face. It is also one of the few where a handful of small changes can make an immediate, measurable difference.

New Zealand imports all of its refined fuel. The country's sole refinery at Marsden Point closed in 2022, leaving us entirely dependent on international shipments. Roughly half of what you pay at the pump goes to tax, levies, and emissions costs. The other half covers the imported product, shipping, distribution, and the retailer's margin. When global oil markets tighten or the New Zealand dollar weakens, the pump price climbs quickly.

In early 2026, conflict in the Middle East pushed 91 octane past $3.00 per litre nationally, with some Auckland stations exceeding $4.00.

You cannot control any of those forces.

What you can control is how much of your money you hand over each week. Most guides on this topic list minor habits and hope for the best. This one ranks the changes by what actually moves the needle for New Zealand drivers, with realistic dollar estimates throughout. The examples below assume a roughly 50-litre weekly fill for a typical urban household; your numbers will vary, but the relative impact of each action holds.

Where You Fill Up

This is the single biggest lever most drivers have, and it requires almost no effort. It matters more than any driving technique or maintenance habit further down this page.

At any given time, the price spread between the cheapest and most expensive stations in the same suburb can be 20 to 40 cents per litre. On a 50-litre fill, the difference is $10 to $20. Over a year of weekly fills, the saving from choosing a cheaper station sits in the range of $500 to $1,000.

New Zealand's discount fuel retailers consistently undercut the major brands. Waitomo, NPD, Gull, and PAK'nSAVE fuel sites tend to be among the cheapest in their areas. Costco also offers competitive pricing, though membership is required. The Commerce Commission's fuel market monitoring has confirmed persistent price differences between brands in the same area, which is precisely why checking before you fill matters.

The easiest way to find the cheapest fuel near you is Gaspy, a crowd-sourced app used by over one million New Zealanders. It shows real-time prices reported by other users and takes seconds to check before you leave the house.

How You Pay

Less impactful than where you buy, but worth capturing if you are filling up anyway.

Most of New Zealand's major fuel retailers run loyalty programmes, and the savings add up when used consistently.

Z Rewards offers a daily per-litre discount plus points redeemable for food, vouchers, or Airpoints Dollars. AA Smartfuel works across BP and Caltex, earning discounts through partner retailers. Mobil Smiles offers per-litre discounts and points with no minimum spend.

Where these programmes become more interesting is in combination. At Z, for example, you can stack your Z Rewards daily discount with a New World Clubcard fuel discount and earn Airpoints Dollars on the same transaction, all through the Z App. No single element saves much on its own, but layered together across a year of weekly fills, a consistent six to ten cents per litre in combined discounts adds up to $150 to $260.

Sharetank: Locking In a Price

Z Energy's Sharetank feature lets you pre-purchase up to 1,000 litres of fuel at today's price and draw it down later at any Z station in the country. You can share your virtual tank with up to five people.

In a rising-price environment, Sharetank can work as a genuine hedge. Users who topped up at $2.50 per litre before a price surge can redeem at stations where the board price has since climbed well past $3.00. The flip side: if prices fall after you buy, you are locked in at the higher rate. Sharetank works best when used opportunistically during price dips, not as a default purchasing method. Check the Sharetank price against nearby discount retailers on Gaspy before committing.

How You Drive

Driving habits matter less than where you buy fuel, but more than most vehicle maintenance tweaks. The gains here are free and available to everyone.

Aggressive acceleration and hard braking can increase fuel use by up to 33 per cent in stop-start urban traffic and around 20 per cent on the open road. These figures come from the US Department of Energy's fueleconomy.gov, and because the underlying physics of combustion engines and aerodynamic drag apply universally, the percentages hold in New Zealand driving conditions. The AA's own real-world testing in New Zealand has produced consistent findings: smooth, anticipatory driving delivers noticeably better fuel economy than reactive, stop-start habits.

The habits worth building:

• Accelerate smoothly and coast to a stop rather than braking hard at the last moment. This single change has the largest effect on fuel consumption of any driving habit.
• Use cruise control on longer trips. It maintains a steadier speed than most humans manage, reducing unnecessary acceleration cycles.
• Consolidate errands into fewer outings. A warm engine is more fuel-efficient than a cold one, so several stops in one trip beats multiple short drives from home on different days.
• Switch off when stationary. Modern engines do not need extended warm-up periods. If you are parked and waiting for more than a minute, turn the engine off.
• Go easy on the air conditioning. It can reduce fuel economy by up to 25 per cent, particularly on short trips and in stop-start traffic.
• Pick efficient routes. The most fuel-efficient route is not always the shortest. It is the one with fewer stops, less congestion, and better traffic flow. Both Apple Maps and Google Maps factor live traffic conditions into their suggestions.

Your Vehicle

A well-maintained car uses less fuel. The gains from each individual action are modest, but combined they make a noticeable difference over the course of a year.

• Tyre pressure. Keeping tyres inflated to the manufacturer's recommended level improves fuel efficiency by up to three per cent. Under-inflated tyres create more rolling resistance, and the engine burns more fuel to compensate. Your recommended pressure is in the owner's manual or on a sticker inside the driver's door frame.
• Routine servicing. A well-tuned engine can be up to four per cent more fuel-efficient. Replacing a worn air filter or a faulty oxygen sensor can have an even larger effect. Follow your manufacturer's service schedule.
• Weight and drag. Remove roof racks and cargo boxes when not in use. At highway speeds, roof-mounted cargo significantly increases aerodynamic drag. Clear heavy items from the boot you do not need for the trip.

Is Premium Fuel Worth It?

If your vehicle's manufacturer specifies 91 octane, use 91. Filling with 95 or 98 in a car not engineered for it delivers no performance or efficiency benefit. At current prices, 95 costs 15 to 20 cents more per litre than 91, and 98 can cost 30 cents or more above 91. On a weekly 50-litre fill, unnecessary use of premium adds $400 to $800 a year for no measurable return.

If your manufacturer specifies 95, use 95. Dropping to 91 in a car tuned for higher octane can reduce performance and, in some cases, trigger engine knock. The owner's manual will state the minimum octane rating. Use it, and save the difference.

What's Not Worth Your Time

Not every fuel-saving tip circulating online delivers a meaningful return. Many persist because they were true a generation ago, apply in overseas markets, or sound intuitively right without holding up to arithmetic.

1. ‍Driving to a cheaper station across town rarely pays off. If the station is more than a few kilometres off your usual route, the fuel burned getting there can wipe out the saving. At current prices, five cents per litre on a 50-litre fill is $2.50. A 10-kilometre round-trip detour can easily cost more in fuel than you save. Use Gaspy to compare stations on routes you already travel.‍
2. Keeping windows up at low speeds to improve aerodynamics is technically correct, but the drag reduction at urban speeds is negligible. At highway speeds the effect is larger, though running the air conditioner as an alternative carries its own fuel penalty. For most everyday driving, this trade-off is not worth thinking about.‍
3. Replacing your petrol cap seal appears on many lists, but a leaking cap seal is uncommon in modern vehicles and will typically trigger a dashboard warning light. It is a maintenance item to address if flagged, not a proactive savings measure.

Electric Vehicles: A Different Equation

If you are replacing a vehicle or buying your next car, the running-cost comparison between electric and petrol is worth understanding. This section is context for those replacement decisions, not a suggestion to switch tomorrow.

At typical New Zealand electricity rates, a battery electric vehicle costs around three to five cents per kilometre to run. A comparable petrol car at $3.00 per litre costs roughly 15 to 20 cents per kilometre, depending on fuel economy. For the average New Zealand driver covering around 11,500 kilometres a year, the annual running-cost difference sits in the range of $1,200 to $1,700.

Since April 2024, light electric vehicles have been subject to Road User Charges of $76 per 1,000 kilometres. Plug-in hybrids pay $53 per 1,000 kilometres. Even with this cost factored in, the per-kilometre running cost of an EV remains well below a petrol equivalent at today's fuel prices.

The trade-off is the higher upfront purchase price. A rough way to think about it: if the EV you are considering costs $10,000 more than its petrol equivalent, and you drive around 12,000 kilometres a year, the running-cost savings take roughly seven to eight years to offset the premium at current fuel and electricity prices. If you drive more, or the price gap is smaller (as it increasingly is with used EVs), the payback shortens. If you drive less or plan to change cars within a few years, the numbers may not stack up. This is exactly the kind of calculation a financial adviser can help map against your broader goals.

The Bigger Picture

Every dollar you save at the pump is a dollar available for something more productive. The actions above can realistically save a New Zealand household several hundred dollars a year, and in a high-price environment like the present one, potentially over $1,000.

But there is a ceiling to what savings alone can achieve.

"Saving on fuel, groceries, and insurance is smart housekeeping, and every dollar counts. But you cannot cut your way to wealth. There is a floor below which your expenses simply cannot go. The families we work with who are in the strongest financial position are not necessarily the ones who saved the hardest. They are the ones who found ways to grow the other side of the equation: investing consistently, focussing on earning more in a strong career, or simply making sure their money is working harder than a savings account ever could."

Joseph Darby, CEO, Become Wealth

Even $800 a year, invested consistently over a decade, compounds into something very different from the same money evaporating at the pump week after week.

If you have tightened up your household costs and want to ensure the difference is going somewhere productive, a conversation with a financial adviser can be a good starting point. Even a straightforward review of where your money sits can reveal whether it is keeping pace with inflation or quietly falling behind.