Drivers are being warned to avoid certain petrol stations if they wish to save money.
Fuel at motorway services is often pricier than at supermarket stations.
This is because petrol firms have a "captive audience" at services, experts say.
Drivers are being warned to avoid certain petrol stations if they wish to save money.
Fuel at motorway services is often pricier than at supermarket stations.
This is because petrol firms have a "captive audience" at services, experts say.