Brits could use a little known rule to cut their petrol bills by as much as £150, as the cost of living crisis deepens, and it's even advised in the Highway Code.
Petrol prices have been soaring with inflation in recent months and now sanctions on Russia as a result of the Ukraine invasion is also having an impact.
But by simply switching off the engine while waiting in queues motorists could save hundreds of pounds, reported BirminghamLive.
Motoring experts have said that cutting the engine while stationary could mean drivers end up spending £150 less on petrol per year - and it is recommended by the Highway Code.
By using this simple trick where the ignition is switched off as well, motorists will also be doing less damage to the environment.
The advice comes as drivers continue to be clobbered by record fuel prices as petrol reaches an average of £1.65 per litre.
MotorEasy founder and CEO Duncan McClure Fisher said: “One thing many people do that is entirely unnecessary is to leave their engine idling.
"This can be done first thing in the morning to ‘warm it up’ or when stuck in traffic.
"Even dropping off something at a friend’s house can see people leave the motor running instead of turning off the ignition.
“While this might seem very innocent, research has shown an idling engine can burn through three to four pence of fuel a minute.
"If you are doing 10 minutes of warming up, five days a week, and spending another 30 minutes per week stuck in traffic – that adds up to a very handy £166 a year that’s being wasted.”
Figures from data firm Experian Catalist show the average cost of a litre of petrol at UK forecourts has increased by 16 pence in the past month.
RAC fuel spokesman Simon Williams said: "With the spring statement just a week away, drivers will be looking to the chancellor to end their misery by cutting duty or VAT.
"One thing's for sure: simply reiterating that fuel duty has been frozen at 58 pence a litre simply isn't going to cut it."