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Old 07-23-2015, 03:51 PM
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Old 05-04-2011, 04:05 PM
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Exclamation 4.8 fuel economy

i purchased a used 2008 silverado 1500 lt 4x4 in december of 2010. i purchased the truck for transportation reasons. I travel extensively for work averaging 200+ miles daily. with technology as it is today is was positive that this truck would get decent fuel economy being basically a stripped down model regular cab shortbed. nice looking truck without many otptin but being a bigger guy it provides my with comfort. after putting several thousand miles on the truck the best mileage that i can get is 14.1mpg on straight highway driving. i drive with traffic at 70-75mph. my tach reads from 2300-2500 rpms in overdrive. i have 285 /17" tires on factory aluminum wheels. I have talked to several owners with larger engines and trucks and they report 17-19mpg highway. what could be wrong? what do i need to do to improve fuel economy? please do not tell me to go slower. what can i do to improve this? a programmer? i have a flowmaster exhaust and k&n aircleaner, changed the plugs and run synthetic fluids. i am stuck with the truck for several years so i would like to cure the problem. any input would be greatly appreciated. can i add aftermarket accessories to the engine, headers,ignition, heads, cam ???? again any information would be helpful. i looked at jegs and the only performance parts for this engine was for a camaro.
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Old 05-04-2011, 04:28 PM
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how much extra weight is in the truck? by that i mean equipment or tools etc. excess weight can have a major affect on your mpg. Also things like running your AC all the time is probably worth another 1-3 mpg.
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Old 05-04-2011, 07:17 PM
Mille Racer 69's Avatar
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Well 1 problem you have are those 285 tires.
If you were to get 245 or 265 you would notice an improvement right away.
Also, up to 45mph roll down windows to keep cool.
above 45 mph roll up windows and use AC for better aerodynamics and fuel efficiency.
Also, above 65 mph fuel efficiency starts to decrease fast.
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Old 05-04-2011, 07:55 PM
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Location: Chesterfield County, VA
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I have a 2004 Silverado (about 90k on the odometer now) that is 2wd, extended cab, long bed; with the 5.3L V8 and an automatic tranny. I have a 3.73:1 axle (which harms fuel economy), 17" wheels shod with P265/70 Michelins and dual Flowmaster '50 Series' mufflers.

With no extra weight in the bed (save for two bicycles), I get 14 or 15 miles per gallon in "city" driving and 18 to 19 miles per gallon on the highway at a steady 70 mph with the cruise control set. At 72 miles per hour, my engine turns about 2100 RPMs.

This is like pushing a brick through the wind, I know, but I did not buy my Silverado to be an economy car. I have my old '02 Sentra with 120k miles on it for "commuting" duty. It gets 30 to 32 miles per gallon, even when driven in a rather spirited manner.

P.S. Inflate your tires a few pounds over normal, don't carry around a lot of junk and drive as though you have a raw egg underneath your accelerator pedal.
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Old 05-04-2011, 09:17 PM
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i have a bone stock 2000 reg cab long bed 4.8 1500 4wd auto with 8400 miles on it it is basically a new truck .i get 15.8 driving around the bronx which is no easy thing to do.its wild here bud believe me.
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Old 05-05-2011, 01:33 AM
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how many miles? may need to clean the injectors. and as driving habits go, acceleration is a major factor. i run 285's as well and even when i drive less spiritedly i only get about 11 mpg, and it sucks. but, even if it got 5 mpg and gas got up to $12 id still drive it, no more cars for me
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Old 05-05-2011, 04:23 AM
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you read it right 8400 !!! miles onit .its a long story.but in reality its a new stock truck
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Old 05-05-2011, 03:41 PM
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285s with what gears? 3:42 or maybe even 3:23 im guessin...get a tune to help with the mileage. I got back 3 mpg and I drive the same way as before. Was averagin 12.5 with 33x12.5x20 with stock 3:73 gears and 5.3 in my 01 then got a K&N filter, free flowin exhuast(straight through design, not that flowmaster crap), and the tune, now im at 15.5
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Old 05-06-2011, 12:08 AM
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Location: Buda, Texas
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It's my opinion that the v6s and smaller v8s are underpowered to pull such an un-aerodynamic object through the air. As was mentioned, keeping 70-72 as your top speed will help, don't punch it when you have to accelerate, and probably get a little bit narrower tires. I have a 5.3 in my truck with 255s and even when I drive a little more aggressively, I still don't ever fall under 16 mpg average for a tank. I'll get 17.5+ mixed city/highway if I drive nice...
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Old 07-22-2011, 08:23 PM
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I put a edge evolution programmer on my 4.8 and seemed to get the milage better, also helps set the tire size through the programmer whixh helps and makes the truck shift better and be more efficient, i also run 285s
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