What’s the worst fuel mileage you’ve gotten out of a road vehicle?

By Colin Wood
Jul 22, 2021 | Fuel Economy

Photograph Courtesy Dodge, Illustration by Colin Wood

Don’t get us wrong, we like to see ourselves as smiles-per-gallon over miles-per-gallon people, but we can also appreciate not having to frequently stop for gas on longer drives and road trips.

That said, forum user A 401 CJ wanted to know what car, truck or road-going vehicle you have driven or owned that returned the worst fuel economy–excluding military vehicles.

Perhaps not surprisingly, a number of you retold stories of fuel economy well below 10 mpg, even going so low as 2 mpg in some instances at the time of writing.

Think you have a vehicle that gets even worse mileage? Go share it over on the thread here, but let us know what sort of tips and tricks you use to maximize fuel economy below.

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View comments on the GRM forums
malibuguy GRM+ Memberand HalfDork
7/21/21 5:57 p.m.

One of my older Malibus had a combination that averaged about 12-14 on the highway...it got old very fast dailying it 80-90miles a day on high test.  Plus my GF at that time lived 35~miles away

My first tercel track day car got 17mpg at Summit Point, 14.5 after the turbo and big injectors.  Still got around 35 highway.

These days my worse offending vehicle is my v6 awd highlander.  Averages 19-22 in my mixed driving.  Steady state highway distance traveling its 25-27.  Everything else I own (that runs) is all 35+

RichardSIA Dork
7/22/21 12:12 a.m.

"Excluding military", spoilsports!
Used to have a big block Ford 4x4 PU that got six MPG, loaded or empty, uphill or down.

Worst at the moment is my 81 Chevy 3500. Despite adding a troublesome FiTech injection and NV4500 overdrive it still does <10 around town and about 12 on the highway.

The rest of the fleet ranges from 15 - 47.7.
But the 47.7 car is to be scrapped so the engine can power something more interesting.


JesseWolfe Reader
7/22/21 7:32 a.m.

1978 Southwind motorhome with a 440, dad and I drove it across the US summer of 95'.  It averaged 7 MPG, thankfully fuel costs back then were an average of .69 cents a gallon. 

pinchvalve (Forum Supporter)
pinchvalve (Forum Supporter) MegaDork
7/22/21 8:04 a.m.

I went 4 miles and went though 12 gallons, but I assume a leaking fuel tank doesn't count.

NickD MegaDork
7/22/21 8:30 a.m.

1995(?) F-350 4WD with a 460. Loaded, unloaded, uphill, didn't matter, it always got 8mpg. But, it would pull anything you threw at it. That truck was an animal.

jwagner (Forum Supporter)
jwagner (Forum Supporter) Reader
7/22/21 11:47 a.m.

'77 Delta 88 with the 403 V8.  13mpg average.

Edit - thinking about it, my '07 MX5 used to get about 6-7mpg on the track, so I suppose that's worse and within the context of the question.  I'm sure other cars have been worse on track but I never checked gas mileage.

philacarguy New Reader
7/22/21 1:08 p.m.

Towing a 20' car hauler (enclosed trailer) kills the mileage.  My 2010 Expedition gets about 7.5 mpg with the trailer behind and my GT6 in it.  Without the trailer, I get about 17 on the highway at 75 mph.  My prior 1999 Suburban was about the same.  It was the same when I had a steel Haulmark trailer as it is now with an all-aluminum Worthington.  Must be just about purely a function of wind resistance.

I think my GT6 with triple webers gets about 8 mpg on the track, though I never really track that accurately.  It's also constantly between 4500-7,200 rpm.

My ideal tow vehicle would be an SUV body (love being able to put everything inside an 8' long cargo space with the seats down) on a 3/4 ton pick-up chassis with a diesel, or a new Ford Godzilla motor or equivalent.

ErnieN85 New Reader
7/22/21 1:28 p.m.

Snow plow truck about 2-4 Mpg

Corvette on track about 2

Mr. Peabody
Mr. Peabody UltimaDork
7/22/21 3:26 p.m.

55 Chev with a built 350, 4 spd and 4.10 gear initially, then later swapped to 4.88-1.

I have no idea what the fuel economy was but I was driving it when I was courting the future Mrs. P, and though she didn't live far away, I was spending $50 a weekend in fuel. in 1984 prices.

I'll have to do the math and get back to you

Woody (Forum Supportum)
Woody (Forum Supportum) GRM+ Memberand MegaDork
7/22/21 5:57 p.m.

I had a '67 Plymouth Belvedere II in high school with a V8, a broken gas gauge and a hole in the tank.

I used to put 5 gallons in every two days, which would pretty much keep the level below the hole. 

And every other trip to the gas station, it got a quart of oil and a quart of transmission fluid. 

That car was my worst offender. 

81cpcamaro Dork
7/22/21 8:31 p.m.

1979 GMC Dually 5-6 mpg pulling trailer, with a 350 SBC. Put a 454 in the truck and was getting 8 mpg pulling same trailer.

Jim Pettengill
Jim Pettengill HalfDork
7/22/21 11:30 p.m.

4 mpg in an agency owned 1977 Dodge Ramcharger 4WD with the 318.  It was at 50 mph into a steady 50+ mph headwind at 90 degrees crossing the Navajo reservation.  Under those conditions that was top speed, floored the whole way.  Usual mileage was up around 12 - 14.

maj75 (Forum Supporter)
maj75 (Forum Supporter) Dork
7/23/21 8:36 a.m.

They all beat the .5-.6 mpg for my boat ;)

DaewooOfDeath SuperDork
7/25/21 10:32 a.m.

1989 Merc 420SEL used to get 13-17 mpg, which is incredibly bad for a 4.2L engine with mild cam timing in a 3700 lb sedan. Never did figure out how sporty V8 stuff like a C4 Corvette could almost double its fuel economy, or how it managed to be less efficient than a lifted 98 Ram with a 360. 
My Genesis Coupe got 20 ish city and 27 ish highway before the tune. After the tune is does 23 ish city and 30 ish highway. The Daewoo racecar I built with my middle school kids would get 14 mpg on track, even after we swapped in the "big block" taxi engine. 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
7/25/21 11:19 a.m.

I built a 468 BBC for a 73 Impala station wagon and swapped the rear for 3.42s to match the cam/weight.  Drove that thing cross country twice at 9mpg.  No matter how I tried, I couldn't get double digits.

Dad had an 88 chevy TBI truck that never broke 12 and got 7mpg towing.

1988RedT2 MegaDork
7/25/21 12:19 p.m.

1985 Chevrolet C30 Dooley, 350 gas, 350TH, 4.10 Dana 70HD rear.  Reliably gets as much as 9 mpg, but I haven't really checked it in a while.

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