Tire size makes a difference. A wider tire has a larger contact patch and will need a lower tire pressure. The factory pressure will work well with a stock width tire. Your pressures sound about right for a car with wider tires, like maybe 275s up front and 295s out back.
36 in my 275 Nittos. I hear people tell me all the time that that's too much, but my current set is wearing as evenly as I think is possible, and they've got 35k miles on them now with at least another 10k left.
I'm running 35 all around as well on stock size. Get pretty good MPG out of that. I do notice that as the tires lose pressure, mileage certainly suffers. Getting about 21 mpg (combined) right now on 35 psi. Possibly more since spark plugs were changed; haven't yet gone through a full tank after the plug change.