More research, from Emissions Analytics, found that the impact of air conditioning on hybrid fuel economy was almost twice as much.
Fuel efficiency dropped 6.1 percent in a hybrid car on average, compared to just 3.8 percent for standard petrol car and 4.6 percent for a diesel.
Mr Evans continued saying: “While the 45mph line is a good guide, things get a bit more complicated when you are in bumper-to-bumper traffic.
“In these situations, it is probably best to avoid using air con or opening your windows.
