Having air-con on in the car & petrol consumption?

[70sCarpet]

I've been told, though I don't know whether it's true, that having your air conditioning on in your car massively increases your petrol consumption. Is this true? I have a long drive to do in Thursday's predicted heat.

It does affect it. Not massively as in halving your range but you will use more fuel with the air con on.

Probably by 10%. My car is a dacia with a small engine an d struggles in heavy traffic if the aircon is on. Bu t this is one of those weeks when you need it!

Mine is effected enough for me to notice it.

Generally about an 8-10% reduction in fuel economy. So if you're usually 40mpg you'd drop down to 36-38. It depends on how hard its running and other factors (efficiency, outside temp etc.)

Still better than having windows open though.

Yes. I notice it.
I have an eco drive on my car and it usually cuts off when the air con is on.

It's not enough to not to have it running on Thursday,it'll be essential,if you have it then use it!