2012 Prius Two not II Lower Mileage After Service

Hey all. Long time lurker, first time poster!

So I took my Prius in for the 60,000 mile maintenance. Nothing out of the ordinary. However, I have noticed significantly lower average gas mileage after the service. It was getting an average of 47-51, and now I'm getting a lower average (I clocked at 38 at the lowest).

I haven't changed my driving (though shortly after the service, I did put about 500 miles on it over the course of a few days with no noticeable difference on those two trips). I checked the air pressure (fixed it up to the higher PSI), checked the oil (it's exactly filled, not overfilled), gas is standard that I've been using, so no changes there. We checked the 12v and it was low (at about 3/4 charge), we charged it with the battery charger per the book. Got a little bit better mileage.

One thing I'm noticing is that, when I used to start going, in EV mode/gliding the mpg gauge would sit at the top and I could accelerate more without it dropping. Now, if I'm accelerating it seems to drop faster, and sometimes when I'm going the mpg gauge stays way down, and when I'm braking or gliding in EV mode the gauge stays way down. Sometimes if I get going it even stays barely above the dash line, way below 25mpg, until I accelerate and then it jumps up.

Any thoughts? The battery seems to have held the charge after we charged it, no further issues there so far. I'm about to set up to take it in for service again to have them look again, but I'd love to be able to take care of it myself.

I have a 2012 Prius Two not II, for reference.

 

The 12v battery, when we checked it, was between the green 100% marker and the yellow 50% marker on the battery tester/charger (my partner tested it, not me, so...) Looks like it's pretty near full currently, it's held the charge it seems. Hybrid battery seems okay, though the temperature has been up and down since I did the service, and the last fill up. Hybrid battery has been discharging, and recharging, per normal it seems. Hybrid battery is sitting at 5 bars of charge right now.

They didn't rotate the tires; they had only rotated them when I bought it used about 3000 miles prior, they stated they didn't need to. Otherwise they did all the standards for 60,000 service.

It's just weird. I know the mpg readout was higher when the car would start and get going, especially after going and gliding/no pressure on the gas pedal, and it seems like the engine is kicking on (but this is supposed to warm it up, right? I don't see any movement in the charging system). I've also checked on the emergency break (seems fine, not overtight, clicks into place after 7 clicks).

 

Yeah. Oil, filters, cabin air filter, all fluids, 5 point inspection... they did drop the tire pressure but we own a compressor so that was a fix we did, oil levels weren't overdone, the things I found doing all of this research. I wonder, if the battery discharged, if it is just needing to 'relearn' some of my specifics? I got it up to 54mpg once yesterday doing in-city driving, but it's more consistently running around 39ish, though I had it as low as 35 at one point (though that was a hyper short trip). I used to get it regularly 46-52, without much variance lower.

I'll take it to a battery place and have them test it, see what they say.