Fuel millage

[scottydl]

I'll put you all to shame... 1995 Suburban C2500, 454 TBI, 4.10 gears. All stock on intake, exhaust, tire size.

10.5 - 11 mpg mixed (that's about 80% highway for daily commute). That's on summer blend gas, and it drops around 1 mpg with winter blend... that's a thing in the Midwest.

I'm lucky to see 6.5 mpg towing my 9000# 35' travel trailer... and 5.5 - 6 is not uncommon!

 

[kennythewelder]

I'll put you all to shame... 1995 Suburban C2500, 454 TBI, 4.10 gears. All stock on intake, exhaust, tire size.

10.5 - 11 mpg mixed (that's about 80% highway for daily commute). That's on summer blend gas, and it drops around 1 mpg with winter blend... that's a thing in the Midwest.

I'm lucky to see 6.5 mpg towing my 9000# 35' travel trailer... and 5.5 - 6 is not uncommon!

OUCH

 

[scottydl]

The highest number I ever calculated was 12mpg, on 95% highway driving right after I bought it and drove home from Indiana to Illinois. That's as good as it gets with this monster powertrain!

 

[PlayingWithTBI]

Time for add-ons and a tune!

 

[Trenton]

My old truck was a stock 1998 c1500 scsb with the 4.3 Vortec and 3.42 gears. I averaged 14 in light traffic and up to 20 mpg on the highway. Only change was using Amsoil in the engine.

My current truck is a 1998 Chevy K3500 Crew Cab Long Bed SRW with the 5.7 Vortec and stock 4.10 gears. Mods include Summit Racing performance distributor/ignition coil/8.5mm spark plug wires, Volant cold air intake (dry filter), Gibson Cat-back exhaust, Black bear tune (set for higher octane, 33s, and deleted rear O2 sensors) 6 inch Rough Country lift, 285/70R17 E Nitto Ridge Grapplers, dual Group 34 batteries, the cats fell of somewhere, and I have Amsoil in everything but the trans. Back in Texas I averaged 9.8 around town and maybe 11ish on the highway, highest I saw was 12.3 when i had 265/70r17 Michelin tires. Since moving to Colorado (8600 feet elevation) and switching to 93 octane, I still average about 10 around town, but I've seen as high as 16.8 on the highway. Really hard to believe, but that was hand calculated over 2 fill-ups of 200ish miles on my drive to Telluride.

Although, when I moved here, it was full blast A/C and 90ish degrees outside for most of the trip. I averaged between 12.3-13.4 mpg the whole way here, over 1100 miles or so.

Even towing a trailer I never see a huge drop. I pulled my buddies '82 D150 once for about 220 miles and I averaged 10.1 the whole way (mostly highway, with some city driving).

 

[TravisR]

• 1990 ECSB K2500, 5.7 Auto, 3.73 gears, stock tire size: 13.9 avg, 17.6 best
• 1991 RCSB C1500, 4.3 5spd, 3.08 gears, stock tire size: 19.4 avg, 20.3 best (only two tanks)
• 1992 RCSB C1500, 5.7 Auto, 3.08 gears, 275/60R15 tires: 15.1 avg, 15.4 best (only two tanks)

I also have a 1990 RCLB K1500 4.3 5spd 3.42 that has yet to finish it's first tank since I got it in January. I need to drive that one more. The 90 K2500 went back to my Dad for now and the 91 C1500 was sold.

I know fuel economy and a love for GMT400s usually don't mix, but it does for me .

Some day, I want a 4.3 RCSB with the highway-est gears they came in and the larger fuel tank (does it fit in a short bed?). I just want to see what kind of mileage I can get and how far I can go on a tank.

I track my fuel economy on Fuelly:

90 K2500: http://www.fuelly.com/car/chevrolet/k2500/1990/travisr/538340
91 C1500: http://www.fuelly.com/car/chevrolet/c1500/1991/travisr/647426
92 C1500: http://www.fuelly.com/car/chevrolet/c1500/1992/travisr/947135

 

[kennythewelder]

I had a 93 WT LWBRC with a 4.3, 4L60E and it had a 32 or 34 gallon tank. The tank was under the bed, so I would thing there is room for the bigger tank, but the tank would be under the cab some what. Maybe a safety issue why they didnt use a bigger tank on a SWB.

 

[RonRonnster]

1998 ECSB here with the 5.7, 4L60E, 3.73 14-bolt, and 100% stock. I run 265-75-16 Wrangler Duratracs. I get 12 MPG consistently all city driving with lot’s of A/C. Running 85 octane, that’s “regular” here in the Rockies. Never drive on the highway so I can’t say what I get there but maybe I should plan an interstate trip just to know!

 

[RichLo]

My MPG is ..... Not good

I started measuring it in my head once and got scared where that number was trending so I stopped.

 

[Tomcat58]

Post your MPGs city- HWY. What year, what engine, mod or OE, what gears you running, and what size tires. Mine is a c1500 97 Vortec, exhaust, tuned for premium, and I get 11 city 16 HWY. 342s and 275/60/15s. I met up with a guy at the gas station last fill up, who clammed 16 city and 20 HWY. Same truck. I said man you must have 273 gears. So post yours and let see what everyone else is getting.
Thanks in advance.

I have a 1991 C2500 5.7 350 and a 4L80e long bed and went on a 1000 mile trip a few weeks ago. Twice I checked the mileage and both times I got 17 miles a gallon. I had check the timing and it was 2 degree's BTDC and it was getting 14 MPG then. It seems by just setting it to 0 degree's it jumped to 17. I check it twice because I couldn't believe it gained 3 miles per gallon but it did Now on my way back home it dropped to 10 MPG but thats to be expected with the load I pickup.

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