What is 'normal' for electric/ICE balance? Getting low MPG, trying to figure out why.

So, I picked up a 2005 Prius a few months back to fix up (it had not been kept up well by its previous owners, and has over 260k miles on the odo) and both have as a temporary vehicle while I worked on my wife's car and then to sell after resolving its issues. It has largely been the car I've driven for the last few month as my other car is a relatively inefficient and finicky exotic that just isn't well suited to winter driving.

It's pretty consistently gotten in the mid-30's for mileage in my mostly short-trip driving around town- the bulk of my driving of it is the 3.5 miles to and from work (most of the time I bike). It will get solidly higher when driving on the highway- I drove it about and hour and a half each way on the high way and it knocked the average MPG up into the low 40's. Everybody I know (which is very few, and none local unfortunately...) who owns a Prius is shocked at how low the mileage I'm getting is. It's still better in-town than anything else I've got or have driven (my bicycle aside), but seems to be way lower than what it should be getting.

To me, it seems like it is far too eager to kick the ICE on and really resists running in golf cart/stealth mode, especially when starting off from a stop. Unless I'm starting with the nose pointing at least slightly downhill the the ICE will kick on almost immediately, usually not much above 10MPH. If I'm on an upward incline it pretty much does turn on as soon as I let off the brake and push on the gas. If I've managed to feather it into running electric-only at speed, it will stay there reasonably well if I'm on level ground or headed downhill, but when I encounter any kind of hill and it will take a bit more power it kicks the ICE on. This isn't always easy to show- but thankfully I have a ELM-327 and an app that lets me log data from it, so I have a plot of speed & engine RPM. Unfortunately I can't upload it from my work computer and will have to do it from home later. :/

I've not seen any OBD codes that would indicate problems with the traction battery, and have not had the Triangle of Doom ever come on- but I also at the moment do not have a Mini-VCI to be able to really look into things, largely because I don't have a laptop that can run the software so picking up the mini-VCI alone wouldn't do me much good. Unfortunately the logging app (Dash Command) doesn't seem to have the custom PIDs for the Prius, but another one (EngineLink) that doesn't log but will show more of them lets me pull up the PIDs for the voltage out of HV Blocks 1-14, and I haven't ever seen more than a .05V or so variance between blocks.

The current MPG doesn't bother ME that much as it is still much higher than any other options, but expect when it comes time to part with it that if it's only getting in the 30's it's going to be a concern. So, I want to figure out what the issue is- and ideally, fix it for as little cost as possible. I can do most anything I need to with regards to cars & electronics myself, so that helps a fair bit.

So, I'm curious as to what I'm seeing indicates from everyone else's experience and what the steps to take to figure things out should be. Thanks!

 

Somewhat questionable- I'm actually waiting for a chance (hopefully will get it tonight) to try and swap the current battery out for the old battery that came with the car. It's a long story- it's already been discussed a good bit (very heatedly, at times...) in a previous thread: Time to replace the aux battery? | PriusChat

I'm planning on resetting it and seeing what the true highway MPG is when I head out on a highway drive tomorrow, I can see about the in-town test later. The grill blocking is an interesting idea, I'll have to look more into that.

 

I needed to make the highway drive regardless, so it was happening anyway. Ended up averaging about 45mpg for the 80 mile or so each way drive, generally doing the speed limit (70). Haven't had a chance to take a long drive on surface streets- driving 20 miles on 30-40 MPH roads isn't the easiest here because it's herd to go that far on what one we have...

Tried uploading the graph, but for some reason it keeps failing...
40 mp