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improving gas mileage on surburban 98

I have a 98 suburban with the 5.7 liter engine. Driving a careful 55 mph gives me 21-22 mpg on the level in Iowa, On hills and winding roads drops down to 19-21 mpg. Driving freeway speeds with the air running and keeping up with traffic going 75 mph drops me down to 17-19 mpg.

I am interested in knowing if I can do anything under the hood to improve mileage, Ive seen electric fans, synthetic oils for the gear boxes yet I do not want to venture into this area because I suspect I may be wasting money by getting 0.00001 mpg improvements, but then, I dont really know.

Also, can I do anything with aerodynamics to reduce drag....fold back mirrors (maybe this is extreme) for example, airflow deflectors..etc???

How about the daylight running lights, anyone know what shutting these down will do?

Any ideas?

Reply to
hardworking
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Consider your self lucky your getting that good of mileage. Thats good mpg inho.

my 92 blazer with the 350 gets 16 on a good day. and Its half the size of your suburban.

Reply to
mudmonkey

Our 99 Jimmy gets 15-16 on the highway if were lucky and all we got is the

4.3L.....Dont even wanna discuss what it gets in town.....that explains why its been sitting for almost a month now.
Reply to
Adam F.

buy a different car. That's pretty damn good mileage for what you have there.

DRLs might cost you .0001 MPG. That's the least of your trouble!

Reply to
burntkat

Per hardworking:

On a good trip, I get 14.7 highway.

Once I got 16....

Reply to
(PeteCresswell)

Yes lucky indeed, do not touch a thing except maybe tire pressure. I have a 89 4x4 burb that will do about 19 mpg at 65 mpg on a trip from Ohio to South Carolina on one tank of fuel (565 miles on 30 gallons of gas and it holds 40 and A/C was on too) Never checked it on long a pure flat land test in recent times. It has stock sized smooth tires with 3.73 gears, a large single exhaust with a flow master (3 inch exhaust and it is quiet in car) and it has 175k miles on it too. I also use premium fuel in it year round (occaisionally 89 in winter but it is rarely drive in winter) and the timing is set 8 BTDC as the baseline. It never ran as well or delivered much over 15 MPG when it ran on 87. Runs like a champ in current setup. I have had it since new and plan to keep it at least till kids are done with college in another 6 or 7 years.

Reply to
SnoMan

Just an FYI - thats about the same I get on my Avalanche. No one ever believes me.

Reply to
cybercoaster

Try a couple tanks of higher octane gas and you may be surprised.

Reply to
SnoMan

Something is wrong with that 99 then. My old 94 with 4.3 gets 18 around town and closer to 21 on the highway. The 2002 we just picked up got

22.4 on the road last weekend (534 mile RT to Cabelas in PA.).
Reply to
Steve W.

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Reply to
Shep

Reply to
Robert Ball

Your getting great mpg! Try getting 12 city and 14 highway.

Reply to
Bill

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