So my vette has left me clueless. I was getting 18 in town and almost 21 on the highway not too terribly bad but not great. Since then the gas milage has gone down to 13-14 in town and 15 on the highway. I went to autozone and had the computer scanned no codes. No lights, tire pressure is good, already did a new fuel oil and air filter. Checked the plugs (they were a charoal grey type color but still really clean and only 30k miles on em) so Im thinking 02 sensor but wouldnt that throw a code? please help thanks guys!