Question: Isn't the A.C. / compressor disconnected from the drivetrain in the Prius? If so, this would be the reason it doesn't drop ... or drop so much on the Prius.
Originally Posted by TheLandYacht
Yeah...but that's nearly 20%. That seems a bit excessive. In the prius, the hit from the AC was closer to 3% even in the dead of summer driving across the state under the direct sun. In the truck, the gas mileage sucks so much already, I don't know if you even notice it.
I have limited experience with the Prius, just drove them when I worked at the Toyota Technical Center. But say your driving the Prius on a typical Texas balmy 100°+ day. When that car is approaching a stop, the engine typically turns off. Yet the A.C. keeps right on cooling. That tells me that the A.C. compressor is not powered by a belt on the engine. But probably turned by an independent electric motor.
The drop in mpg on the Prius due to A.C. use would have to be due to the increased run time of the gas engine to charge back the batteries due to the increased electrical drain of a motor turning the A.C. compressor.
And yes, I think the loss due to A.C. use on the Mirage is quite large. Much larger than the additional drag of rolling down the windows. If I can roll with the windows down and NOT sweat, that's what I do. I use A.C. very little.
View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.5 L/100 km ... 51.0 mpg (Imp)