Lower MPG




The OP may just see the MPG reduce more now when it has been quite hot around the country. It could be the compressor runs much stronger and longer now compared to "normal" summer temperatures.
In my area A/C runs compressor 100% for 8-9 months of the year so it is easy for me to see how much it helps MPG when I turn A/C OFF.




Yet my mpg for those months is lower than in summer.
Biggest difference with mpg comes between driving around Las Vegas, what I consider mostly city, although we drive lot of freeway, when every few months we drive to San Francisco and then mpg goes up about 20%, regardless the fact that 80+ mph we use is not economical speed.




Yet my mpg for those months is lower than in summer.
Biggest difference with mpg comes between driving around Las Vegas, what I consider mostly city, although we drive lot of freeway, when every few months we drive to San Francisco and then mpg goes up about 20%, regardless the fact that 80+ mph we use is not economical speed.
Just turn the A/C off while cruising at highway speed and look at the MPG value how it goes higher. You should be able to drive about 5 minutes and still get cold from the vents.




