If you're travelling over Christmas, you might want to plan your journey to avoid paying through the nose on your snack stop.

Those who regularly take a break on long journeys will know that service stations can be on the pricey side, but new research has found that motorway munchies cost more than twice as much on average than the same supermarket snacks.

A mystery shop at 21 motorway service stations across the UK to gather prices for seven common items has revealed motorists are paying on average 117 per cent more for the same goods compared to a supermarket.

The items in the mystery shopper's basket were: 

  • a cheese sandwich
  • a refrigerated sausage roll
  • a packet of ready salted Walkers crisps
  • packet of wine gums
  • a bar of Dairy Milk chocolate
  • a bottle of Coke and
  • and a bottle of water

Bottled water saw the highest mark up at service stations across the UK, not least because the item is available for free with a refillable bottle at all service stations.

Beaconsfield services in Buckinghamshire was the worst offender, charging an extra £1.85 for a 500ml bottle of water than the average supermarket cost of £1.67.

Durham services was home to the most expensive basket of sweet and savoury snacks and drinks. At £16.21 the same basket of goodies cost almost £10 more than the average supermarket price of £6.89.

Both Lancaster and Woolley Edge services ranked as the second most expensive services, both coming in at £16.17 for the same items.

Heart of Scotland services (Harthill) in North Lanarkshire was the cheapest place to stop for snacks on a motorway, where motorists would spend £9.31 - 43 per cent less than Durham.

The UK's top 10 most expensive services are: 

Durham Services (A1M, North East)

=2 Lancaster (Forton) Services (M6, North West) 

=2 Woolley Edge Services (M1, Yorkshire)

=4 Hilton Park Services (M6, West Midlands)

=4 Leigh Delamere Services (M4, South West)

6 Beaconsfield (M40, London)

7 Bothwell Services (M74, Scotland)

8 Magor Services (M4, Wales)

9 Birchanger Green Services (M11, London)

10 Reading Services (M4, South East)

The research found that motorists in the South West are facing the highest snack tax for convenience. The North East was the second most expensive region, the South East the third priciest, and Scotland was the cheapest region for service station snacks.

Top tips for saving money on a long car journey:

  • Plan ahead and buy food in from the supermarket before you set off, or even better take a packed lunch and refillable water bottle from home.
  • Use an app such as refill.org.uk identify places to refill water for free.
  • Fill up on fuel before you get onto the motorway to ensure you aren’t paying inflated prices.
  • Bring some activities and snacks for the children so you are prepared should they want to stop off to avoid expensive treats.
  • Consider pulling off the motorway to a nearby supermarket if you need to re-stock: prices are considerably lower.
  • Don’t forget to make sure you carry out all the appropriate vehicle checks before you start a long journey – checking tyre pressure and water levels will mean you travel safely and don’t have the unexpected cost of a broken-down car.

Clare Egan, Head of Motor Product at Admiral Insurance, who commissioned the mystery shopping research, said: “We all expect to pay a little more for convenience, but the amount people are charged at service stations amounts to highway robbery in some cases.

"Grabbing the essentials from home or at least a supermarket before setting off could result in some big savings on the overall cost of your journey."

“Given the availability of free water refills at all of the service stations and the push to be plastic-free, motorists don’t need to spend anything on bottled water, let alone a forking out as much as 420% more than in a supermarket.

“Many of us will be making cross-country trips with our families over the coming weeks, and it will be tempting to stop en route for a snack or petrol. By planning ahead, you could avoid the hyper inflated service station costs save some money for Christmas and help the environment at the same time.”