Fuel loyalty schemes are marketed as if they'll transform your motoring costs; most are worth less than a penny a litre. The one scheme that reliably beats the market by 5–10p isn't a loyalty card at all — it's a warehouse membership, and whether it pays depends on maths almost nobody bothers to do.

Costco: the breakeven maths

Costco's forecourts consistently price petrol and diesel 5–10p a litre below nearby supermarkets, which are themselves usually the cheapest thing in town. The catch is the door policy: you need a membership, around £34 a year for an individual, and the pumps check it.

So run the numbers. At a 7p-a-litre saving, £34 is covered after roughly 490 litres — call it a 45-litre tank a month. Fill up more often than that, or run two cars on one household membership, and Costco fuel alone justifies the card before you've bought a single oversized tray of croissants.

Two caveats keep it honest:

  • Location. There are only a few dozen Costco forecourts in the UK. Every extra mile you drive to reach one costs you roughly 15p in fuel — a ten-mile round-trip detour eats most of the saving on a small fill
  • Queues. The price is no secret; weekend peak times can mean a fifteen-minute wait for the pumps. Weekday mornings are calmer

If a warehouse sits on a route you already drive, this is the single biggest recurring fuel discount in Britain. If it doesn't, skip it without regret.

The loyalty schemes, ranked by honesty

Every forecourt brand now has an app, and they all follow the same pattern: real but tiny.

  • Tesco Clubcard earns points on fuel at a rate that works out around a quarter of a per cent back — about a third of a penny per litre
  • Nectar at Esso and Sainsbury's forecourts lands in the same territory
  • BPme Rewards, Texaco Star Rewards and Shell Go+ trade mostly in occasional offers and hot-drink perks; the fuel value averages out at well under 1p a litre

The verdict is the same for all of them: scan the app if you're on the forecourt anyway, and never cross town for points. Driving a mile out of your way to earn 15p of loyalty value while burning 30p of fuel is the exact transaction these schemes hope you won't examine.

The voucher promos worth an actual detour

The exception to the pennies rule is the periodic supermarket voucher: Morrisons, Sainsbury's and Tesco all run waves of 5p-off-per-litre promotions tied to an in-store spend, typically £40–60. On a 45-litre fill that's £2.25 — modest, but you were doing the shop anyway, and it stacks on top of supermarket fuel that's already among the cheapest locally. The move is simply to notice when a wave is on and time your fill-up to the voucher's window rather than letting it expire in the glovebox.

Where never to fill up

Motorway services price fuel 20–25p a litre above the supermarkets — £10 or more on a full tank, for the same unleaded. The rule: fill up before you join the motorway, and if you misjudge it, put in £10 to get you to the next town and finish the job there. Airport-adjacent forecourts play the same captive-audience game with hire cars. No loyalty scheme on earth claws back a motorway markup.

The premium fuel question

While we're at the pump: super unleaded typically costs 10p or more a litre over standard, and for the overwhelming majority of cars it does nothing measurable. Unless your handbook specifically requires a higher octane — a handful of performance engines genuinely do — the premium nozzle is a £5-a-tank donation to the forecourt. The same goes for branded 'performance' diesels. If you want your engine to feel looked after, spend the difference on tyre pressure and a service; both actually show up in the consumption figures.

The saving bigger than any card

Here's the uncomfortable one: how you drive is worth more than every scheme combined. Sitting at 60mph instead of 70 on a motorway run cuts consumption by roughly 10%. Properly inflated tyres are worth a few per cent more. A roof box left on out of laziness can add up to 20% of drag-driven consumption at speed, and stringing short cold-engine trips together burns fuel at its very worst.

A typical 40mpg car doing 8,000 miles a year gets through roughly 900 litres — around £1,250 at recent prices. A 10% efficiency gain returns about £125 a year. That's three years of Costco membership, or roughly four hundred years of loyalty points.

The cards are pennies theatre, pleasant enough while the tank fills. The discount that actually moves the needle is the fuel you never burn.