Hey jeep lovers, names Rob and I just bought a 2012, 2 door, Sahara w/manual tranny. I have to say that after 1100 km's I am super impressed with the overall refinement of the JK!

I just wanted to share what I thought to be interesting. I have fueled up twice thus far, both times running the gauge down until it was exactly at the empty line. Now, my first fill up was regular unleaded which after 505 km's I need to refuel, my second fill up was w/premium (10 x air miles!) and to my surprise, when that needle got to the empty line, my trip A read 601 km's! My driving habits were, and almost always are the exactly the same, so I'm wondering would premium fuel really give me almost 100 km's more than regular would? I mean it did, so I guess I'm really wondering if anyone else has experienced the same thing?

And I am loving the forum so far, tks!

 

There are more factor then driving style to take in were you topless and doorless more during the first tank? I find that I drop rough 3 mpg if I pull the top and doors off. The engine also has a break in period and your fuel efficiency should increase once you reach that point.

 

Also as you break in the motor the gas mileage can improve some, not sure about that much though. What you have to figure is it worth spending the extra $ for the extra miles?

 

A few months ago someone posted on here who had methodically kept all fuel records for his Jk over about 58,000 miles of driving. Within the data was some regular gas as well as higher octane. His conclusion was that higher cost for the higher octane was not worth it. I have 5700 miles on my JKU manual with 3.73 rear. I am keeping records on all my fill ups. So far I see anything from 15.9 up to 18.8 per the computer. Also got 10.5 while towing, but that's another story. For my jeep, the computer is typically within 0.5 mpg compared to hand calculation. My point is that only two fill ups is not enough data to make a determination.

 

Octane has nothing to do qith gas milage. The octane number represents the amount of cylinder pressure the fuel can handle without combusting prior to the spark.

The only factor that certain locations may find to generate a benefit is ethanol as not all areas add this to higher octane fuels. Ethanol is cleaner for the environment but less efficient.

Using premium can actually damage your engine over time as it produceses higher cylinder temps which can pit the top of the piston as well as other damage.

 

All vehicles have an OBDII that has a fuel/air mixture programed in it. Higher octane will not help. It is a placebo... if I pay more, I might subconsciously drive s bit more careful resulting in better mileage. Rain, wind, traffic, temperature, etc... all play a role in MPGs. Octane does not.

 

As stated in another post, check on the ethanol content. It can make a big difference in millage.

 

We're pretty much the same here in the US. We can however in places find premium non ethanol (most of our premium has it).

Thought I heard a week or so ago it's sounding like we may be moving to 15% in the coming years as well.

 

I run midgrade in my JK and i'm averaging 17.6 to 18.5 and have got 19 twice, just depending on the conditions. I know the station I fill up the most has 10% ethanol. I've been told the only stations left that don't have enthanol are Shell and BP but may be others. I'm also running stock and have not started mods yet.

 

I'm running on premium right now and I'm getting 19.4 right now. If you keep the engine RPM's around 2000-2100 you should see a good average for fuel mileage. Also that is just with me driving around town and on the highway.