Dealership causing low mileage?

Hey, all.

I bought my used Prius last November. I was getting an average of 50-55mpg right out of the gate. There was some minor damage to the driver front quarter panel that the dealership sent it to a body shop to get fixed about a month later.

After the repairs, I my first tank got me 40ish. I filled up the air in my tires and got back up to 45-50, but still not where I was at. I figured it was the onset of winter (even tho this change occurred suddenly and persisted in warmer days).

Now, 2 months later, I just had my Prius in for its first maintenance since I bought it (dealership includes a 2 year maintenance plan with all used vehicle purchases). This was for tire rotation and nothing else (they tried to sneak a hybrid battery fan service in for like $200 without telling me, but I'm pretty sure I can figure out how to do that once it warms up a bit).

I was getting about 42-48mpg in winter before I brought it in (could sometimes hit 50, never saw it below 42).
Literally, as I pulled away, I started getting 35-30. Current tank is average of about 33. It also made a weird sound a few times while turning, from the drivers side rear area (I think), but I figured that might have been related to the snow/ice on the road. Kind of like a tire squeal (not traction control).

Any ideas? Input? The first time I took it as just coincidence, but twice (and with that big, noticeable jump) is starting to get me suspicious that they're doing something funky or just wrong. They also told me that the drop was 'due to fuel additives in winter' when I called them back, later. I'm going to test the 12v battery and check the tire pressures after work, today (and make sure the lug nuts are actually on there, and tight), but with it just being a rotation and billion-point inspection or whatever, I've no idea where to start after that.

Note: If I don't find anything wrong, I'll go through the big list of things to mention about the car to help narrow it down, I just wanted to know if anyone had any instant "oh, that same thing happened to me it was this" type of responses.

-Jon

 

Thanks for the input, all. I think I identified the sound and one of the sources of the mileage loss. There was a chunk of snow/ice still hidden up in the wheel well that rubbed against the tire when I went around a corner (suspension compressed = slight rubbing). It was solid black road ice so pretty clear why I didn't notice it.

Cleaned out all the wheel wells and pumped the tires back up to 44 or so (instead of 36 where they set them). Instead of the inital 32mpg, it's at about 39-41mpg or so, now. I'm going to run a fresh tank and measure it at the pump as was suggested, but I don't have too high a hopes for that making too much of a difference. I have noticed that sometimes it feels like the ICE will run for no reason at all (engine is warm, sitting at a stop light/coasting down a hill/etc, heat is off, ac is off, hybrid battery says full, in 'eco' mode, engine is still running away).

The car has just shy of 58k on it. I've been driving it a lot more than the previous owner did. Speaking of previous owner, I know the car is capable of good mileage over time. The trip-a was set when I bought it with 4500 miles at 56mpg(this is after how ever much test driving, etc, it went through).

 

... I just remembered, I completely forgot to reinstall(replace actually) my grille block. That may have been contributing to it, too, since my standard daily commute is only about 15 minutes and that extra warming would really matter. I'm going to install that this afternoon, refill the tank, reset all my measurement tools and see where I'm at. in a couple weeks.

I'll also be taking a moment after I get home to feel all the brake rotors to see if any of them are particularly warm. And, finally, checking the 12v battery for deficiencies. On that front, was there ever a consensus on the 'bigger batter = better' debate?

 

Figured I'd update anyone who was curious. Now, 3 weeks later, my fuel economy has mostly returned to normal. I don't know what all the issues that combined to make it poor were, but I'm hitting about 60mpg average right now (according to MFD at least) and, for a while the other day (running errands all day) broke 82.7 over 25 miles (my new record).

I still never reinstalled the grille block (never made it to home depot, and the weather has gotten warmer anyways). I've also been incredibly careful about my driving habits, much moreso than I ever was before. Parking with the hood facing the sun, even. It's still possible that my mileage is slightly less than it would have been before the service, but there's too much changed between then and now. I also suspect the tire wear has 'evened out', improving it until the next rotation.

Regardless, the standard suggestions seemed to help (as well as CLEANING OUT THE SNOW from my fenders) such as tire pressure. I'll be making a 200 mile highway run this weekend, so hopefully I don't ruin my 60mpg for this tank.

As for H. S. over there... I'd check my tire pressure. Seems like dealers like to fill them to 35 rather than 42, and that's a pretty big difference. Also the 12 volt battery.