AC and MPG
 

I have a 2013 ES350 in So Cal. Does using the AC on a high fan speed cause the gas consumption to increase?

I picked up my 2016 in March. I live in Tucson so AC is on most of the time. I will will know the difference come Nov/Dec. I can say that the avg mpg I get is 23/24. This is mainly in town driving.

Hope this helps a little.

i have an es300h... so far, i'd have to say it's a hit of about 5 mpg... here are my observations overall from nj...

spring: 41 mpg - no a/c
summer: 41 mpg no a/c
summer: 36 mpg with a/c
winter: 36 mpg
winter: 32 mpg w/ winter tires

50/50 mix of city/hwy

I do not think the fan speed would have an effect on gas mileage. Running the AC at any fan speed should consume the same amount of fuel. Just MHO. :)

I agree. Any effect that fan speed has on fuel efficiency should be negligible.

Also note that AC systems in modern vehicles are quite efficient. With both my ES and with other relatively recent vehicles that I've owned, the fuel efficiency hit that I have seen from running the AC has been less than 1 mpg. Further, fuel efficiency will be better with the AC running than it would be if you had the AC off and were driving with the windows open, which would compromise the aerodynamic efficiency of the car.

In climates with cold winters, there can be a significant drop in mpg with winter driving because it takes longer for the vehicle to reach normal and optimal temperatures, and during the time it takes for the car to warm up, there will be a significant drop in mpg. Depending on how often the vehicle is shut down and how often it is re-started and needs to warm itself up again, there can be a drop of 25% or more in mpg during the winter, and that drop is significantly greater than any drop in mpg caused by using the AC during the summer.

Anytime you turn the A/C compressor on, it will put an additional load on the engine. Therefore, there will be an increase in fuel consumption. How much of an increase will be somewhat subjective.