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

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 …

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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+

"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.

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. 

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

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.

'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.

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.

Snow plow truck about 2-4 Mpg

Corvette on track about 2

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

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. 

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.

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.

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

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. 

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.

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.

When I sold the Volvo 144 rally car the new owner paid me an extra $400 to deliver it. 

We wanted to get back home in a hurry and I was driving 75-80mph. 

My 1974 Ford F350 got 4 mpg.

My dads '68 Oldsmobile 98 - 455cid, 4-barrel, premium fuel and my 16 year old right foot.

10 mpg

I've been pulling 9.5 from my excursion.

I once was able to get 21MPG in my '93 F150.  Brakes were bad and it was a week till I could afford new.  Accelerated slower than a fully loaded semi, coasted to a stop wherever possible, all the hypermiler tricks.

Same truck now gets 8-9MPG because the #5 cylinder has so much blow by that its sucking oil as much as air and fuel.  I shudder to think about my catalytic converter.

1996 Dodge Ram 1500 4x4 w/360, 8-10 city / 12 hwy, mpg towing was horrid.

Replaced it with an '02 F350 diesel that got 18 all day.

Many vehicles in the single digits, over the years. Worst offender? 07 Toyota ... 17 - 19 combined, 17 - 19 Hwy. And I am known for successfully driving for one or two mpg better than others in same car. Toyota should be ashamed of themselves. 
Couldn't complain about the 18 mpg on the brand new 2021 Ford Ranger... except it was advertised as 28. Flat out lying to the public, to meet requirements, and the public eats it up. 

Pulling a light trailer + light car from Austin Texas to Socal with a 90s Chevy SBC van .

I think the Cat was clogged and the O2 sensor was iffy , but I just wanted to get home .

It would do 50-55mph and not much more......it's 1500 miles !