Fuel discount cards: how they actually work, and what they are worth
A card in your wallet can shave a few cents off every litre, but only if you know what it really saves and use it where it matters. Here is how brand and loyalty discounts work, and how to get real value from the one you already have.
How a fuel discount actually works
Most cards work one of two ways. Some knock a fixed amount off the price per litre, so many cents cheaper at the pump, applied automatically when you pay with the card. Others give points or cashback based on how much you spend, redeemed later rather than seen at the pump. The first kind is easy to compare, since it is a visible price change. The second takes more work to value, because the saving is hidden in a rate you have to calculate yourself.
Doing the maths on your own card
Turn any card into a single number: cents saved per litre, on average. A flat discount already gives you that number directly. A points scheme needs converting, work out what your typical redemption is worth in cash, divide by the litres it took to earn it, and you have a comparable rate. Once you have that number for your card, you can weigh it against the price gap between stations honestly, instead of assuming the card always wins.
The trap: loyalty to the wrong station
A discount card against simply picking the right pump
Typical card discounts compared with the gap we measure between the cheapest station in a city and the typical one.
Fillz, live station prices in ten European cities, measured on 2026-09-08. Card values are illustrative.
The point is not that cards are worthless. It is that a card discounts whatever price you were already going to pay, so loyalty to a dear station can leave you behind someone with no card at a cheap one. Use both: pick the cheapest pump first, then spend the card there if it is accepted.
A card tied to one brand only pays off at that brand's stations, and the temptation is to always drive there even when a competitor nearby is cheaper before the discount is even applied. A few cents off a pump that was already 15 cents dearer than the one next door is not a saving, it is a smaller loss. The card is worth using when it is the tie-breaker between similar prices, not an excuse to ignore better ones.
Stack it with comparing, not instead of it
The two habits work together, not against each other. Compare the real prices around you first, then apply your card's saving to whichever of those stations accepts it. Fillz does exactly this: set your discount once, and every result already includes it in the total, so the station it highlights is the one that truly leaves you with the most money, card and all.
Common questions
Are supermarket fuel discounts worth having?
Often yes, particularly flat per-litre discounts tied to a shop you already use. Worth it depends on the size of the discount versus how far out of your way the station is.
Should I always use my discount card's station?
No. Compare first. A card only helps if the station it works at is not already the expensive option once the discount is applied.
How do I compare a points scheme fairly?
Work out the cash value of a typical redemption, divide by the litres needed to earn it, and you get a per-litre rate you can compare directly against a flat discount or a cheaper station.
Set your discount once, use it everywhere it counts
Add your card or loyalty discount in Fillz's settings, and every comparison already accounts for it, so you always see the station that genuinely pays off, discount included.
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