Could be both. I am very pleased that I use OEM pads and rotors. My 97 4runner has non-oem rotors and drums and I am having horrible gas mileage in it. Worst than the LC. I am saying all these small factors contribute to the overall performance of a vehicle. It is not just a good engine.Are you saying the rotors or pads cause the drag?
What pad and rotors are you guys using on your 100 series?
OEM front brake pads are made by either NBK or Sumitomo (depending on which part number you use). Rears are made by Akebono.OEM rotors. To many aftermarket rotors made in China, have run-out issue. They also seem to rust fast. Excessive rust and the disk may separate.
OEM pads with OEM anti squeal shim kits. Or save on shim kits with premium ceramic Akebono pads. It's been suggest OEM are made by Akebono. Akebono come with attached anti squeal shims.
Replace those rear slide pin boots, if any concern as to condition.
OEM and most front pads, come with attached wear indicators. Rears do not. Make sure to install a set.
OEM front brake pads are made by either NBK or Sumitomo (depending on which part number you use). Rears are made by Akebono.
And +1 on the slide pin boots! Good idea to regrease them every once in a while too.