Surging prices at fuel pumps have led to an increase in the number of motorists driving off without paying.
Forecourts have reported three attempted thefts a day on average, with a 39 per cent increase in reports of non-payment between January and May this year.
It comes as the average cost of filling a family car with diesel at motorway service stations has hit nearly £2 a litre for the first time - or £110 a tank.
Diesel prices at motorway forecourts hit an average 200.99p on Thursday, the latest 24-hour period figures are available for, meaning a 55-litre tank would cost up to £110 to fill.
Petrol on motorways could also soon surge past the landmark after hitting 197.18p a litre, and both fuels passed the £100-a-tank milestone this week.
Across all forecourts, the average cost of a litre of diesel rose to 188.82p from 188.05p. Petrol went from 182.31p to 183.16p. It means in one week alone the fuels have shot up 3.81p and 5.28p, adding £2.10 and £2.90 to the cost of a fill-up respectively.
The AA, which is calling for ministers to slash fuel duty by another 10p, said high streets are losing out on more than £20million a day in potential customer spending due to them needing to shell out so much on fuel.
AA President Edmund King said: “High streets are already reeling from families cutting back in this cost of living crisis. With soaring petrol costs, shop tills are haemorrhaging £23million a day to fuel.
“Worse still, as the holiday season approaches, UK tourism will see millions of pounds of potential spending by visitors lost to higher petrol costs at forecourts along the way. This is the worst week of pump pain so far for drivers.”