I have a 2007 Night Runner Durango with the 5.7 Hemi Motor and 50,000 miles. Can anyone give me an idea of what "Normal" fuel mileage should be for this vehicle. Now I am not one to think that a 5.7 HEMI is going to get 20mpg in the city, but I have cleaned the throttle body, new air filter, synthetic oil etc and I am only getting between 11-12mpg with a mix of city and highway driving. Is this normal mpg for this vehicle?

 

Even with Agressive tread offroad tires, I get 14 city, used mostly in rush hour comiting trafic. 16-17 with part highway mix in rushhour traffic

 

What fuel are you using and what tires?

Even with the MDS, if you have a slightly heavy foot, the HEMI will still drink gas.

 

BFG ATs, Same diameter but wider. 87 octain, non oxiginated ethinol summer blend, Valero or Chevron gas only.

MDS won't help in the city, But those clean burn summer blend fuels they use in most metro areas will hurt your milage. And a Hemi will drink all it can if you let it.

 

I am running the factory sized 17" BF Goodrich Tires and running 87 octane fuel I normally fill up at Walmart or Costco gas stations. As I said the truck has bout 50,000 miles on it and I have yet to do a full tune up on it. Was unsure of the time frame to change them on these motors. Should I change the plugs and wires? Does it make that big of a difference on mileage with the HEMI's?

 

Have you not changed them in 50k miles? If not, then yes, changing them should help at least a little.

Some people argue that all gas is the same. While it is true that a lot of oil pipelines and other things are shared between companies, most stations have their own blends of additives that they mix in with their gas. Sometimes its for advertising, sometimes its for winter or summer, sometimes its to dilute the gas to make their costs cheaper.

The Walmart and Costco gas will hurt you. I've compared Walmart, Hyvee, BP, Shell, Cenex, and Casey's General Store gases so far in my region. Shell, Hyvee, and Cenex (regional company I think) work well. BP gas is OK, tends to hurt my mileage by about 1 MPG on average. Walmart and Casey's General Store gas hurt my mileage by 2 MPG. Those results are from my Ram, your results may vary.

Before we bought the Dingo, the wife drove a 2004 Jeep Grand Cherokee 4x4 with the 4.0 I6, and it HATED Wally world or Casey's gas. Even shut off one time leaving a Casey's, just quit for no reason as we were pulling away from the pump. Her mileage went down from 18-19 highway to 16 with that gas. Even gave them a second chance later... same results, although it didn't shut off that time. I am never testing that gas again.

 

I average 13-14 MPG with Shell 93 octane,
FF

 

Will have to try throwin a set of plugs and wires on it and see how it does. Will also try changin up the fuel and look for some improvement. While I am changing the plugs and wires on this beast is there any other "Normal Wear n Tear" engine items that should be changed as part of a tune up which might help?

 

Nightrunner:

Since you have an 07 with 50k, I would replace the plugs (all 16 of them). Unless your wires have been damaged, they should be fine.

My 04 just turned 68k with original wires, and it runs like a top.

Not sure what mpgs you are expecting, but your Durango weighs roughly 5200 pounds and has the aerodynamics of a barn door.

The window sticker on my 01 4.7 was 14/18 mpg. The sticker on my 04 Hemi reads 13/17 mpg.

I have found those numbers to be pretty much spot on.

Not that will help your mpg issue per se, but at 50k changing the fluids in your transfer case and differentials along with a transmission fluid/filter change is a good idea!

Use Mopar or Valvoline ATF+4 for the trans and transfer case. Mobil 1 synthetic 75/90 gear oil for the diffs.

Don

 

As of the last two tanks. I am getting 16.4 in the city with 20's on 275/55's. I'm pleased to say the least.