Okay, I've had my Prius over a month now and I checked my tired pressure yesterday. The first thing I noticed was how low the factory default tire pressure must be. My front Tires read 36 and 35 and the two back tires read 32 and 34. Judging by this, I am guessing the factory default is 36/34, or thereabouts.

Does anyone know what the factory defaults are?

Knowing that I have been getting around 60mpg the last two weeks or so, I am going to raise my tire pressure to 40/38 to see how my mileage may change to do some testing myself.

I am wondering if any detailed analysis has been done comparing the relation of MPG and tire pressure. I know that many have said their higher tire pressure has resulted in higher FE, but I have not seen any graphs or reports on this topic in detail.