New 12v Battery & Eco Tires Didn't Help MPG Drop

Hello, please redirect to a sticky if I'm overlooking some troubleshooting tips. I tried looking but didn't find any.

Late last year my mileage dropped from about an average of 55-57 mpg per tank to around 50. At the time I needed new tires, and one had a slow leak, so I thought that was the culprit. After I got new tires (Michelin Energy Saver A/S) I calculated the mpg average after two tanks. Oddly enough, I had my top two worst averages ever. 49.7, then 48.3 mpg!

So, then I came to this site and saw many similar posts with suggestions about the 12v battery. So, I go to Pep Boys. They test the battery and tell me that I do need a new one.

Well, I'm still on my first tank, but I can tell already (via the car's trip odometer average and closely monitoring the 5 min consumption display) that there's been no improvement. My driving style, routes, and the weather all have minimally changed or not at all.

I'm planning on taking it in to a shop, but I want to know what to ask for.
What's wrong with my Habanero? (my nickname for the C)

Some stats: 2013 Prius C one; 46,000 miles; last oil change 6K miles ago
THANKS!

 

Thanks Padroo. Is that something I can do myself by chance?

 

Uh, thanks, but I think you posted this reply in the wrong section.
I was wondering about DIY MAF Sensor cleaning. Still open to hearing an answer! Thanks.

 

Thanks for all the replies.
I'll check the sticky.
The back seat vents should be clear, but I'll double-check.
I don't know the history of the battery. I got the C used 2 years ago. I didn't run down it need a jump since I've had it.
To be honest, the guy at Pep Boys did the reading on the battery and I took his word for it.
I live on the peninsula. You have a local recommendation?

 

I read the sticky (I did see some of it before posting), but what stood out were comments about the warm-up period. Then it occurred to me, this is the only thing that changed in the last 6 months. I moved much closer to work. I have two offices, one is 9 miles away and the other is 3 miles. I think this is the reason for the MPG drop.
I just finished my first tank with the new battery and it was 50.4 mpg, so, still no difference.
I wish I had been monitoring and keeping regular notes, but stopped last Summer. I moved in the Fall of 2017. I was often doing the math at the pump, but didn't write it down, but know that I noticed the drop sometime late last year. My gut tells me this is it.
Thanks for the assistance!

 

Had to come to the forum for other research, but figured I'd give an update.

My drop in mileage was not due to moving closer to work. In fact, it was the horrendous Bay Area traffic that was giving my mileage a boost when I was living further away! At that time, driving in the slowed traffic was great for my MPG. I was averaging a slow, steady 30 MPH or so for most of the the 35 miles going to work (i.e. primarily using the battery). I figured this out in the last few months as I took some trips to San Jose after work--which was heavily congested. My average mileage on those legs was close to 60 MPG, which was where I was averaging per tank before I moved.

At least the godforsaken traffic was good for something!