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My 2000 Jeep Grand Cherokee Ltd, with 4.7 liter 235hp V-8, automatic transmission is mostly driven in South Florida. It is NOT a 4 wheel drive. About 80 percent of my driving is on the highway, where I have been getting consistently over 25 mpg, with Air Conditioning turned OFF. Using Mobil 1 for oil since the car was new.

EPA rating is 15 city, 20 highway. If I were getting this mileage, I'd trade it in for a sub-compact!

I average about 55 to 60 mph on I-95, or on the turnpike, when everyone is doing 70-80. I have to pay close attention to my rearview mirror, but I have had no problems co-existing with faster drivers. FWIW, my mileage goes down significantly if I drive 65 mph or above, or use the airconditioner. I can get 525 miles from a tank of gas, with some reserve.

I haven't gotten a tuneup in 20,000 miles, and now have 46,000 on the odometer. Anyone have any tips for further improvement on my mileage. Which items changed during a tuneup potentially improve mileage, i.e., sparkplugs, aircleaner, etc.

1) Oil - there are some real experts here on the subject, but it'll be syn. oil

2) Pump up tires to max sidewall - search here for posts on PSI you'll see what people are putting in their tires (I run 50 psi which is max sidewall, no issues for 25,000 miles)

3) get rid of all unecessary 'stuff' in the car - I 've been carting around 300 lbs of my daughter's apartment boxes for a week. It has subtracted 10% off my MPG.

4) get a Scangauge or similar iFCD - it is surprising when you can see gas consumption in real time - how much your MPG will improve - the feedback is priceless.

5) Practice some DWL

Welcome !

welcome, excellent job. i am sure with your attitude you can increase it even more.

I think your numbers are pretty good. With today's high quality mineral oils the only advantage to synthetic engine oil is extended oil changes. Being most of your driving is highway your oil isn't getting abused. You may want to get some information from some of the other members on the addition on a front spoiler to your jeep. If done right you should see some improvement at highway speeds. I would swap out the factory transmission and differential oils for synthetic. Although they are the greatest benefit in colder climates they will help some in the Florida heat.

Mobile 1 is synthetic isn't it?

Be sure your tires are aired up to their max sidewall pressure, it's the PSI rating printed on the side of the tire.

And also, bust out your manuals and see what regular maintenance needs to be done. Do you want that jeep to last you 200,000 miles or do you want to be shopping for a new car when it hits 60,000 miles cause it hasn't been properly maintained?

The feedback in just half a day is fantastic. Thanks very much!!

Time to go change the airfilter, and tomorrow get my differential and transmission oil changed (to synthetic), plus new spark plugs. I'll see what else is scheduled per the owners manual.

Spoiler? Never would have imagined trying this. Will check around.

Last thing - I run at around 34 psi. Higher than that, and it seems to make the handling a little rough. BTW, using nitrogen from Costco.

You'll notice a difference in mileage with higher tire pressure.

I wouldn't pay extra for nitrogen. 78% nitrogen from plain air is enough for me. I doubt there's much difference, especially one big enough to be cost-effective.

Do you have a roof rack? Can you remove it? That'll help cut down on drag.

PaleM -

Costco doesn't charge for nitrogen.

Roof rack - I wonder how it'll "look" without it!!!

Thanks

PaleM -

Costco doesn't charge for nitrogen.

Roof rack - I wonder how it'll "look" without it!!!

Thanks

Your cherokee will look a bit funny without the roof rack, but you won't miss it much. I took mine off in October and have not needed it since.

I appreciate hearing from someone who has actually removed theirs. I was just looking at a Jeep forum that happened to have instructions on how to remove it. Although I will be surprised by any mileage improvement, considering my fairly low highway speed, I can at least preserve it's condition when I should sell the vehicle.

you'll be surprised... the roof rack makes a good deal of drag.
if you don't want to remove it a "fairing" might help (wind deflected! FTW)

I really like the front spoiler idea... the Jeeps weakest point will the the V8 of course, followed by it's brick-like aerodynamics.

You can get a lot of aero improvement by just removing the bars that run side to side.
The parts that run length wise have a much smaller effect on fuel economy.

Just get a beater Civic from 96-00 for around $4000. The gas savings will pay off the insurance plus you can speed 65 mph. That's my situation with my beater HX. But now my HX is my main car.