I have an '03 hemi quad 4x4 towing package with 3.92 dif. Except for the very 1st tank I have used 87 octane. Higher octane is for detination (pre-ignition, knocking). If your engine doesn't knock with 87 octane, you're wasting $ with higher octanes.

Over a 2 year period going 49,000 miles, I have averaged 14.9 MPG (calculated - exactly). My computer is usually off by about 1/2 MPG (on the low side). I do not have a lead foot - but that figure above includes pulling a trailer and driving in 4 wheel drive at times.

You should be getting something more like ~12 MPG.

 

jeff, so u only use 87????????????

 

I agree with Jeff17 above, I've owned the truck in my signature for over a year now and have never had anything but 87 octane in it. The mileage that you are getting is not only low, but it is horribly low, I get 9.5 mpg while towing my T.T. and around 15 on the average otherwise.

It would seem that your mileage is on the "leak" level, almost like you have gas going somewhere else other than through the engine, of course I'm sure this isn't the case, but a good mechanic should be able to discover what it is, if it's that bad.

 

10min is fine for idle in cold winter states i live in michigan where it been in the single digets alot lately. the hemi for me takes a good 15min. to warm up thats with a few mods and 10 degree weather. i get about 9 to 10 miles to the gal. thats with a 4ton foot.

 

Not exactly. The engines are equipped with knock sensors that will take timing out of your engine to prevent knock. When you take timing out of the engine you lose performance. Taking timing out of your engine will also reduce mileage.

I'm not sure what else I can say. It's in the owners manual and you should take a look at it and see what they recommend. If you're running lower octane fuel, you're not getting the most out of your Hemi. I do agree that something more is probably wrong with your engine though.

 

ok guys I just came from the garage and my tire pressure 30lbs in my brand new dunlops 267/70/17 all the way around, and adjust to 38lbs, the truck feel a little better now-getting taylors sparkplug wire set-k&n air filter-and I just spend $89.00 in a set of sparkplugs and the rest of the stuff is coming this weekend- and yes I did beat my friends new titan- boy was he mad!!!! I also have a 3" gibson exaust though!!!!!!!!!

 

ok after I put some air in the tires to 38psi, now the ceiling meter I'm geting 8.8mpg-but this morning I put the truck in the scanner and found that the computer it's only giving 10deg of advance- talk to the guys at the dodge dealers and they couldn't give any timing numbers- but they said it should be more-here we go again!!!!!!!!!!!!!!!!!!!

 

Really for most Mopar smallblocks, that's plenty of advance. I just looked at the shop manual and it says that the ignition timing is not adjustable, but doesn't even give a value.