At the last tune up (In sept) I put a set of NGK platinums in ( I got a cheap deal on them), and since then my average MPG has dropped to about 17 MPG and the highway has dropped to 22-24. Used to be about 18-20 city and 26-28 highway. Im goin back to Champion coppers tomorrow. But why the hell would it get so bad so fast? I though platinums were supposed to last longer than copper plugs The exhaust is black now when I rev it. Everything else seems fine, havent seen a CEL since the TPS went bad long ago.