UK drivers told do not drive faster than 63mph this week
Reducing the speed at which you travel can improve fuel efficiency

UK petrol prices have reached their highest since the Iran war started almost three months ago.
The average price per litre of petrol is 159.43p, 26.6p more expensive than it was on on February 28 when the US and Israel carried out joint strikes on several key Iranian sites.
Iran retaliated by striking sites across the Middle East and closing the critical Strait of Hormuz trade route. About 20% of global oil traded is transported through the waterway and the closure has rocked markets and driven up fuel prices across the globe.
One litre of diesel costs 184.96p, having fallen 6.58p since it peaked on April 15. The price recorded on Tuesday is the first time it has been below 185p a litre since April 1.
According to motoring group the RAC, a 55-litre tank of petrol for an average family size car now costs £87.69 which is £14.63 more expensive than it was when the war broke out. A diesel tank of the same size will cost £101.73, £23.42 more than it was at the start of the war.
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"AA advice to drivers is to use the price tracking available on mobile phone and other apps to find the cheaper fuel stations," an AA spokesperson said.
"These are getting regular price updates from the government’s Fuel Finder scheme. There is a lot of price variety out there if people look – and the cheaper fuel is not always where you think it is. For instance, fuel stations on busy routes may price low to pull in passing trade."
The AA has also given drivers a tip on how to improve fuel efficiency while ensuring traffic continues to flow.
The association has urged drivers to reduce their car's speed by 10 per cent, saying this "improves fuel efficiency" and would ensure they are "keeping up with the flow of traffic".

Its advice would mean that someone would be driving a top speed of 63mph on a motorway, or 54mph on a single carriageway.
Motorists should also steer clear of "continuous harsh braking" by preparing for roundabouts, traffic lights and changes to the flow of traffic, the AA said.
Drivers are in another hit on Wednesday when energy regulator Ofgem announces the latest price cap: the highest a supplier can charge for the July to September quarter.
The expected rise of 13 per cent will add £200 to the average household energy bill.
Oil and petrol prices are likely to remain volatile while the Strait of Hormuz remains closed.