Mileage changing suddenly

[jayal]

I was getting a steady 36mpg in my 2011 Fusion hybrid. A couple of weeks ago, the mileage started dropping, bottoming out at 29 mpg. Now it's gone back up to 33 mpg. I'm driving the same way over the same routes. The only difference is that the weather has gone from hot to very hot. Any idea what's going on? Do I need to have the battery checked?

[dogo88]

I was getting a steady 36mpg in my 2011 Fusion hybrid. A couple of weeks ago, the mileage started dropping, bottoming out at 29 mpg. Now it's gone back up to 33 mpg. I'm driving the same way over the same routes. The only difference is that the weather has gone from hot to very hot. Any idea what's going on? Do I need to have the battery checked?

 

Very hot causes the air conditioner to run more which depletes the battery, which causes the ICE to run more, which increases gas consumption which lowers the MPH you get.

 

Dan

[jayal]

Very hot causes the air conditioner to run more which depletes the battery, which causes the ICE to run more, which increases gas consumption which lowers the MPH you get.

 

Dan

[jayal]

Thanks. That makes sense, but it still leaves two mysteries. First, this is a 2010 car, not a 2011, and it didn't happen last summer, when it was just as hot. Second, why would the mileage drop suddenly, then go back up, when the temperature has remained the same? Is this something I should take to the dealer?

[rfruth]

Sounds like just a battery re-calibration to me

[jayal]

Sounds like just a battery re-calibration to me

[jayal]

Thanks. I'll give the dealer a call.