Ceramic brake pads will eat up the rotors much faster than semi-metallic. If you use the same calipers and the same size pads, the ability to convert momentum to heat will not change, only the rotors ability to absorb heat will increase. Averaging close to 56 mpg, I rarely ever use the brakes, since brake application IMHO is a failure to anticipate oncoming conditions (conservation of momentum). Ceramics are great insulators, precisely what you DONT want when your objective is to convert momentum into heat, with friction.
I run 48 psi, which makes the ride somewhat rougher probably noise levels a little higher.
I could not agree more with foama. Try a mid 1960s car with manual drum brakes, that when you blow out a wheel cylinder the pedal goes to the floor and you grab the emergency brake and pray. Then add manual steering to make any emergency maneuvers much tougher and finally some cheap bias ply recaps. Drivers who faced that environment, would rave about the quality of modern braking and steering systems to say nothing about tires.
View my fuel log 2015 Mirage de 1.2 manual: 55.7 mpg (US) ... 23.7 km/L ... 4.2 L/100 km ... 66.9 mpg (Imp)