Drivers have been warned to not press the air conditioning button as it can increase fuel usage by up to 20%.
Scorching weather has arrived on Merseyside with temperatures expected to reach 28C today. The sweltering conditions have prompted the Met Office to issue an amber heat alert.
The warning is in place until the end of Sunday and forecasters expect "health, transport and infrastructure" to be impacted. Temperatures are already beginning to rise and are expected to peak on Friday thanks to the influence of high pressure.