I have taken a couple of trips in the rubicon with airraid cai and routinely avereaged around 21 mpg on these trips with a best being 24.2 going south on I95 between dc and richmond.
I just drove from Richmond to ATL with the cruise on 70-72 just like my other trips and couldn't get over 17.8mpg. I have changed nothing except the break in oil. I was unable to get my usual oil and put penzoil in it instead.

Any ideas as to what has happened? Jeep now has 4400miles on it.

 

Our mileage dropped alot when they started adding 10% Ethanol to all our fuel here last summer.

 

A possible contributing factor. Depending on where you get your gas, some places, Baltimore being one, just switched over to a new fuel blend for winter. My mileage has dropped about 1,5 per gallon, it does every year. Come April when we go back to regular blend my mileage always goes back up.

 

Did you use 5W/20 oil?

Also, the ethanol gig is a big deal. My Jeep certainly doesn't run as well on any fuel with ethanol and even not being consistent in who's gas I run seems to wreak havoc on the ECM. If I stay consistent on my fuel everything is good on MPG and a change can quickly result in a couple mile per gallon decrease, mostly with where ethanol is added.

 

I normally run the fuel on the army post, However on this trip it seemed that when we needed fuel there was only a pilot truck stop to use. I just dumped some fuel system cleaner into the tank to see if it helps.

 

+1, got to agree with all the above.

 

My milage has dropped between 3 and 4 mpg since winter gas blend and I just broke 4500 miles...35's are on the way so its going to drop even more.

 

try 8oz Militec-1 in your oil. That stuff is great!

 

Looked at the web site and it seems like anothere snake oil to me.

 

Same thing here, 16 before 12.5 now, must be the winter gas.