Motorists in the West Midlands who shop around for cheaper petrol prices could end up stranded during the bank holiday weekend, the AA has warned.
According to the breakdown service, drivers who delay refuelling because of the soaring petrol costs - at a time when 18 million motorists are expected to take to the roads - are at risk of being left "embarrassed" if they have to call out for emergency fuel.
And if prices continue to soar from the current average of £1.12 a litre, they could soon reassess their future plans for bank holiday getaways in the country, the AA added.
A spokesman for the AA explained how the rising costs would affect motorists.
"What it is doing is causing people to shop around for fuel and the risk of that is people will end up running out of petrol as they wait to find somewhere with cheaper petrol and that is kind of embarrassing to have to call the AA to put a gallon of petrol in your tank," he said.
"But I do think it will make people think how they are spending their money and make them think about buying a smaller car or stay in the UK rather than going to the Continent."
Car journeys at the weekend look set to cost the nation's drivers £110 million more than last year and are expected to average 304 miles, the AA said.
Drivers of diesel vehicles will feel the pinch the most - seeing a rise of 29 per cent on the journey and unleaded drivers experiencing a 17 per cent climb year-on-year. As a result, it has warned of an estimated 33 per cent increase in traffic today, with a high number heading for various big sporting events - adding further to the congestion.
The peak will be at about 5pm, with the M6 between junctions 6 and 11a expected to be particularly busy, with the West Country, Lake District and Blackpool being named top destinations.
Among the popular events this weekend are the Football League play-offs at Wembley Stadium, the Scottish FA Cup final in Glasgow on Saturday, the England v New Zealand Test match in Manchester today and the Rugby Union Heineken Cup final in Cardiff tomorrow.
An RAC spokesman said: "We're all desperately disappointed that none of the home nations are going to football's Euro 2008 tournament, but this weekend will be the start of many sports fans' summers.
"It's important for motorists to be aware of all the events which are on and to plan their routes around them, allowing 50 per cent more time for their journey. This is also the weekend RAC patrols really see traffic to holiday resorts pick up with the start of school's half term, and, if the sun shines, we'll be expecting heavy traffic as everyone makes a dash for the beaches."
Other popular destinations include the 21st Hay Festival. Organisers of the 11-day event are predicting the arrival of 140,000 visitors. The festival will feature US President Jimmy Carter, Hollywood star Kathleen Turner, chef Jamie Oliver and former Prime Minister's wife Cherie Blair.
In addition to the predicted congestion, travellers will face disrupted rail journeys and the possibility of poor weather. Forecasters have predicted highs of 19C (66F) in the West Midlands but warned there was a high risk of heavy showers on Bank Holiday Monday.
MeteoGroup UK also said southern England could be hit by thunderstorms sweeping in from the south-west.
A spokeswoman said: "The northern half of the UK should be fine, but we're a bit concerned about the possibility of thundery rain getting into the south."
Engineering work has been scheduled for more than 30 sites on the railways, with services once again disrupted on the West Coast Main Line.