I currently own a 2004 Xterra 2wd, auto and I have noticed a significant decrease in gas mileage. Relative to about a year I ago I believe I was getting right around the norm for highway miles, say 20-22 or so. But now I am only getting about 16.5 and thats with cruise, almost all highway at 70 mph. Which I think is not where it should be. Obviously I didnt buy this car for gas mph but noticing the significant drop concerns me and I would like to get it fixed. I first noticed the problem last summer when I took a trip and I got a wopping 15 mpg. That was a fun 5 fillups over the whole trip....

Anyways I have done all the "known" gas mileage killers, the spark plugs, air filter, plugs, fuel treatment etc. and its gone up to 17. Does anyone have suggestions on what else it could be? Fuel injectors need to be replaced? Any suggestions would be awsome!!

04 Xterra V-6 Auto 50,000 miles 2wd
Live in Dallas so medium to heavy traffic and no mountains or snow :P

Try cleaning the Mass Air Flow Sensor with cleaner that is designed for this job. Check out your auto parts store for a can. Will run about $5 bucks!

Just a suggestion!

You didn't mention that you changed the fuel filter. Also, the best over the counter fuel injector cleaner is BG 44K. Tire pressure needs to be addressed as well. What about oil change intervals? Where are you at on that. And quit picking up 300 lb. hitchikers!