1985 GMC Caballero - Rare?

[Ribbedroof]

231 was not a factory install for 1985 Caballero.

It was available for 1984, but not anywhere near the MPG you are claiming.

https://www.fueleconomy.gov/feg/noframes/27364.shtml

I'd be curious to know what the exact combo in your vehicle is...I have a 90 mile daily commute and the 267/T350/2.41 is FAR from those numbers

 

[Ribbedroof]

Sorry if I come off as rude, I am just skeptical of mileage claims in the mid/upper 20s for cars that have the aerodynamics of a brick (Monte SS is arguably better aero-wise than either my wagon or a Caballero), It seems many people do not actually know how to calculate it. Common to see stuff like "I put $12.00 in it and drove it for 3 days"

 

[84 El Camino 231]

My figures came from a round trip to West Tx (2400mi.) in good summer weather using a/c (one reason this era vehicle appeals to me).

Tires @35psi, single factory exhaust tuned to book using ccc setup operating as intended.

It's been a while since having my '81 305 el camino on the road but it gets at least 20mpg if I recall (good tune using ccc), unmodified in any way. 2.41 rear is a good mpg ratio for 305 th350C IMO. Gotta make sure carb isn't rich, that's the key. CCC working as intended makes sure of this otherwise open-loop (inoperative ccc) can be tuned even leaner than CCC but it takes some fiddling. Make sure mechanical advance is dead on (32-34 total) and carb isn't on the fat side.

Not sure if having the torque converter lockup working helps but mine does work.

That's about it really.... Everything confirmed to book(no guessing), tires @35 psi. Nothing else special done.

 

[84 El Camino 231]

Sorry if I come off as rude, I am just skeptical of mileage claims in the mid/upper 20s for cars that have the aerodynamics of a brick (Monte SS is arguably better aero-wise than either my wagon or a Caballero), It seems many people do not actually know how to calculate it. Common to see stuff like "I put $12.00 in it and drove it for 3 days"

My 69 chevelle 350 2bbl got 15, my 71 318 2 bbl Dodge maxivan got 18mpg. Proper tune has a lot to do with it. I don't think of any g-body as a brick until over 70mph then it starts to matter. Maybe put the tailgate down roll up windows helps. I never tried tailgate down...

 

[Ribbedroof]

So, what is the everyday combined MPG?

 

[84 El Camino 231]

Don't forget, there were two 3.8 motors those days. The chevy version was the early 4.3 block, maybe still odd-fire I think. The later 4.3 came with tbi and that combo should pull close to 25mpg hwy as well I'd expect. Nice setup.

 

[84 El Camino 231]

So, what is the everyday combined MPG?

Highly depends on how it's being driven, my 84 driven on 4 mi trips to the lake weekends gets more like 14mpg.

 

[olds307 and 403]

How heavy is the Caballero? My 3750 pound 88 Cutlass has got 26 mpg imperial with more in it, I am sure. I haven't figured out city mpg but it isn't bad.

 

[Ribbedroof]

How heavy is the Caballero? My 3750 pound 88 Cutlass has got 26 mpg imperial with more in it, I am sure. I haven't figured out city mpg but it isn't bad.

That's about 21 MPG for US gallon.

 

[olds307 and 403]

Like I said more in it, I should be able to hit the high 20's and he is running similar highway RPM with lock up and 2.41's the 3.8 usually come with. It really depends on how he drives, my old 77 Dodge van with a 318 2bbl auto got 19 mpg imperial but it was an originally Slant 6 powered so it may have had deeper gearing, no tach. I may be a touch high but not impossible. I once got 32 mpg imperial with our non od 81 Delta 88, 307/th250c/2.41, usually got mid to high 20's.