Averaging 35mpg

Just the egr pipe?

Tires pressure?

Oil level?

 

Exactly.

 

When was the last time the brake caliper pins have been inspected and re-lubricated?

 

Is 140k miles or kms? Either way, full EGR and intake clean is always a good idea.

 

How did the pipe look like the first time before cleaning? And how many miles was it?

 

good news

 

wow, thats a lot of issues for a '12 with 140k. have you owned it since new?

 

have you checked all the wheels to make sure nothing is binding?

 

I will just say that 50 ==> 35 MPG is a lot of energy lost. It must be going somewhere. Either out the tailpipe as unburned fuel, or maybe as a previous poster suggested, as a dragging brake. A pyrometer to measure the brake rotor temperatures after a long drive might indicate that, or simply jacking the car up and seeing how freely the wheels spin.

Gas smell at tailpipe? Anything surprisingly hot? Anything changed that would dramatically affect the aerodynamics?

My 2012 Prius v gets a little over 40 mpg (always has, even the PO), but we don't drive it like it's a Prius, and the v is known to get lower mpg due to the increased size and weight.

Not sure what to make of the Dr. Prius output there. It seems to say the O2 sensor is both good and bad. A bad sensor would probably cause the engine to run rich, sending unburned fuel into the cat and out the tailpipe.

 

thats close enough. i would get tech stream and pursue any error codes

 

Have you removed and cleaned the intake manifold? Pay special attention to the EGR passages. Clean the intake ports while you're at it.