I have had my 99 z28 auto for about a month now and just put my first full tank of gas into the car. I am at about 1/8 of a tank now and have only gotten 171 miles out of it. Is this about average? I am estimating that I will get near 200 when the light comes on. This is mostly a mix of highway and city driving and I haven't been really getting on the throttle because of the ice and snow. If this is about right, then I guess I have no problems but if this is low, what could be the problem? I have noticed a little loss in low end power and when driving on highway there is a slight odor at times. Could my cat be shot? The car has 44600 miles on it. I know I have a cat back borla system on it but I believe the cat is a stocker. How can I test the cat without taking it off? Thanks for the help guys!!!!!!!

 

Check your tire pressure. Sometimes that helps. It had helped me with my car.

 

Tire pressure in the winter should be looked at more diligintly as well all vehicles will get considerably worse fuel mileage in the winter months. As a note, I have an m6 and when trying hard to get good gas mileage I have hit 31mpg but remember our canadian gallons are slightly larger than the us ones.