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08JeepGC 01-08-2012 03:23 PM

Fuel mileage impressions
 
Hello fellow Jeep Owners. I just bought a certified pre-owned 2008 Grand Cherokee limited with the HEMI December 10th. This is my third jeep. Coming from a 1991 Cherokee XJ then a 1994 Grand Cherokee ZJ 5.2. Both had lifts and bigger tires. BOTH horrible mpg. 13mpg highway in the XJ and 15mpg highway in the ZJ...on a good day.

I knew the mileage would be bad when buying. I am getting 11-13 mpg in the city. I took it on a decent highway tip yesterday for the first time since I bought it and I was very impressed with the fuel mileage.

I got 19.5 mpg with cruise set on 70. MDS was on the whole time and the average was still climbing. The only thing I have is a k&n drop in filter.

Impressive for a heavy jeep with a hemi! :thumbsup:

MattyDipps 01-08-2012 03:32 PM

Re: Fuel mileage impressions
 
yeah thats about right the best ive ever gotten was 22.5 at 60 and the cruise set in my 3.7 and the hemis are only a couple mpgs off from the 3.7s

congrats on the purchase !

oldgeezer 01-08-2012 03:37 PM

Re: Fuel mileage impressions
 
Good numbers(Highway) there. Few questions though? Recent tune up,mileage,etc? I have the 2005 5.7L Limited(Loaded) and combo of city/highway ave. around 14 MPG with my wife driving-she does not "baby" the vehicle for sure. On a trip of approx. 200 miles, I will ave. around 17+. That is pushing at 70+ and no cruise control. I use 87 octane and am reading 83K+. Last major maintenance was at 63K so I am due within another 10K. Overall, no complaint here. Good luck with your new vehicle.

08JeepGC 01-08-2012 03:42 PM

Re: Fuel mileage impressions
 
37,000 on the jeep. Cleaned the throttle body and checked the plugs already. Plugs look good and they don't look worn out. Ambient temp outside was 41 degrees and I use 89 octane. Here in Michigan the winter fuel is horrible. 10% ethanol. I'm hoping when summer comes around I will be able to get more.

jeepgcoman 01-08-2012 05:06 PM

Re: Fuel mileage impressions
 
First, let me say that almost all my driving is between ~2500-4000 ft. elevation. That being said, around town (when I can keep my foot out of it) my Hemi will get about what everyone else gets....13-14 mpg. On the highway, with my mods., I seldom get less than 20 mpg. Most of the time it is between 21-22 mpg, using 87 fuel and the 93 Diablosport tune. The best I've gotten at this altitude is a little over 23 mpg. Last month I took a trip down to sea level for a week, but unfortunately I blew a header flange gasket which ruined my mileage tests. I drove it over 1500 miles this way and still got just over 20 mpg. I was hoping to get between 24-25 mpg at sea level. Maybe next year I'll try it again. Most of my highway driving is usually between 60-65 mph, using cruise control as much as possible.

Walt 01-08-2012 08:55 PM

Re: Fuel mileage impressions
 
Quote:

Originally Posted by 08JeepGC (Post 548257)
37,000 on the jeep. Cleaned the throttle body and checked the plugs already. Plugs look good and they don't look worn out. Ambient temp outside was 41 degrees and I use 89 octane. Here in Michigan the winter fuel is horrible. 10% ethanol. I'm hoping when summer comes around I will be able to get more.

I'm in mid-Michigan. K&N drop-in also. Currently at 74.9K miles.

Normally use 89 octane gasoline (various sources). Recommend you avoid the gasoline with ethanol in it. Tires are 34 psig (cold). Oil is full synthetic.

1. MPG's drop slighly in Winter due to the gasoline blend we get served.

2. Usually see ~14.5 to 15.3 mpg in pure town driving. Rural driving is ~17.5 mpg. I-75 highway driving at 70 mph is anywhere from 18.5 - 19.5 mpg.

08JeepGC 01-08-2012 09:54 PM

Re: Fuel mileage impressions
 
Quote:

Originally Posted by Walt (Post 548464)
I'm in mid-Michigan. K&N drop-in also. Currently at 74.9K miles.

Normally use 89 octane gasoline (various sources). Recommend you avoid the gasoline with ethanol in it. Tires are 34 psig (cold). Oil is full synthetic.

1. MPG's drop slighly in Winter due to the gasoline blend we get served.

2. Usually see ~14.5 to 15.3 mpg in pure town driving. Rural driving is ~17.5 mpg. I-75 highway driving at 70 mph is anywhere from 18.5 - 19.5 mpg.

MPG has not been good in the city due to remote start for 10 minutes then driving 5 miles to work. I think the dealer put 5w-30 oil in the Jeep when I bought it. The MDS would hardly turn on. A few days ago I drained it and put 5w-20 in it. The MDS kicks on all the time now.

DaBigBone 01-08-2012 10:00 PM

Re: Fuel mileage impressions
 
Each tank overall average is around 14ish. On a good day i'll see 18mpg on the highway

Muddy4DSM 01-14-2012 11:32 AM

Re: Fuel mileage impressions
 
I must be doing something wrong. I can't seem to get above 12... and that's with brand new plugs!

dmsfun 01-14-2012 05:46 PM

Re: Fuel mileage impressions
 
Quote:

Originally Posted by 08JeepGC (Post 548257)
37,000 on the jeep. Cleaned the throttle body and checked the plugs already. Plugs look good and they don't look worn out. Ambient temp outside was 41 degrees and I use 89 octane. Here in Michigan the winter fuel is horrible. 10% ethanol. I'm hoping when summer comes around I will be able to get more.


Good mileage, and it should get even better as the engine loosens. The first thing I would do is install a catch can; the gunk quickly builds up and gets baked on throughout the entire intake with al modern hemi's, as you saw with the TB; the CC will also keep your TB clean, and they are simple to install.

lll2for3lll 01-14-2012 05:52 PM

Re: Fuel mileage impressions
 
Quote:

Originally Posted by Muddy4DSM (Post 552401)
I must be doing something wrong. I can't seem to get above 12... and that's with brand new plugs!

That's about right for city. The area you live in might play a factor too. And start using mid grade fuel if you aren't.

Stickerbombed 01-14-2012 07:13 PM

Re: Fuel mileage impressions
 
I think i average 9.5 with the 33s on her lol


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