Those numbers are jeep worthy! Thats no bueno indeed.
Spark plugs can help, clean up your fuel injectors. Both of those are relatively cheap tune-ups that can pickup a few mpg. With gas going up thru the roof you definately want to fix this situation. CAI helps but you still shouldnt be that low.

I juust got a 01 r/t coupe. I get roughly 21 city 28 highway. I do a lot of driving for work and its mostly highway and it does great. no mods even yet to speak of. Hopefully after I get done playing with it we can break 30.

EDIT: (omg a new poster that edits): JudasDeth, in regards to fuel economy.gov. I use that site also. Understand that the government doesnt do much there. Its all user provided info. People put in their numbers. And sometimes there arent even sites for certain model years because nobody has posted any information. Take these numbers with a grain of salt because not everybody is smart enough to calculate their gas mileage. However most of the time if I see a bunch of people putting their digits in Ill believe them.

 

A good question would be how do u calculate your gas mileage? The only really acturate way to calculate it is to fill up your tank till the pump stops then run it down to how ever much u want (i run it down to around a quarter) then fill up your tank full again(when the pump stops) then calculate the miles you went over gallons you bought. If your going by fuel gauge then your estimates could be way off. My strat pops up with the gas symbol with 3 gallons still left in my tank. Its just a percautionary feature so you have some time to get gas before u run out. Now if u do that and still get 21mpg then good for you .

 

I normally put the same amount in every time the gas light comes and calculate my milage from there. This time around I did a complete fill-up and added a bottle of Shell V-Power injector cleaner, took the car for a short highway trip of about 24 miles @70 to 80mph and the rest my normal in-town trips. I currently have 85 miles on a quarter tank of gas thus far, so maybe the V-Power actually is doing some cleaning.

 

Yeah this is pretty much the best way to do it. Although its worth mentioning that if you go until the pump totally stops you have more than the listed capacity usually. since you cant really run it to bone dry its good too to maybe use a marker on your guage. Say just do the top 1/4'th of the tank and just go from that. But it can be off a good bit. Hard to really say. I suppose the hardcore way would be to drive it from totally full to out of gas and then have a gallon in the trunk to get to a station. You would know for sure.