Gas miles decrease when on EV mode!?

I never noticed it, but I wasn't really watching to close either... I had my original tank for 5k miles in my 14 PIP
( it wasn't a fun ride, but I learned a lot about the car and plugin stuff in general etc).
I doubt anyone knows for sure (except toyota) how the car calculates E to empty. Although if you have specific circumstances
as to when/where it happened and how much E went down, I think a lot of priuschat ters will offer their best ideas..
Than you can see if any of them match your thoughts as to where, when and how much...

 

Sure it does. It's estimating how far you can go, period. Not just how far you could go if you only drove in HV mode. So, as you use power from the battery, you use up available range just like when you use power from the gas tank.

You'll also notice that the miles to empty increases after you plug in and charge the battery. Because now you can go farther than before you charged. It's perfectly logical.

 

Yeah, DTE will go up and down based on the battery state of charge.