I'm running stock and get 22mpg. However, I just put new spark plugs in, and after this tank of gas, I'll be doing some calculations. If it's still not above 25 I'm gonna think about replacing the O2 sensor, since it's been 102,220 miles since the stock one that was put in at the factory.
31 with intake headers and exhaust, timing retard, and auto. I am also on factory o2 sensors and its a 98 with 111107 miles cant complain. This is also spraying mabe 2 times on that tank of gas and with 50/50 highway and city. City driving is only in rush hour traffic
The last time I could afford to fill the tank and calculate highway mileage it was 35. Very shocked. That's on a 98 200 5-speed with just under 100k. I've done maintenance but its still on stock plug wires and o2 sensors and a bad alignment. However that 35 mpg was with me and the wife and our 2 small kids in the car. I never expected it. Go figure.