My wind wagons powered by Air Elementals are based on 19 century United States wind wagons.  After all, fiction based upon fact is often the most entertaining fiction.

For my player characters, Air Elemental Wind Wagons, these small yet swift wagons become very useful in situations where it would be unsafe for draft animals.  When far from civilized areas, draft animals are in danger from being eaten by wild animals or monsters.  They are in danger of being stolen by thieves or commandeered by soldiers during wartime.  Also, by being powered by an Air Elemental, a D&D Wind Wagon could be much larger, carrying more people and freight than a real Wind Wagon.

The Kansas Historical Society has an article about Wind Wagons.

https://www.kshs.org/kansapedia/wind-wagons/12239#:~:text=They%20were%20similar%20to%20an,center%20of%20the%20front%20axle

The text reads:  “Along the westward-moving frontier, innovation and invention were requirements for survival and the early American settler was indeed a resourceful individual. It is not surprising that in the latter half of the 19th century ways were sought and found to utilize the energy provided by that great natural resource of the prairie—the wind.

“A novel device of the Kansas territorial period was the wind wagon, sometimes called a sailing wagon. Several were built and in 1860 the press gave them considerable attention. They were similar to an ordinary light wagon; weighed about 350 pounds; had a bed about three feet wide, eight feet long, and six inches deep; and were propelled by a sail or sails raised over the center of the front axle. When the breezes blew in the right direction the wagons were reported to skim over the prairies at about 15 miles per hour, with speeds at up to 40 miles per hour. At least one wagon was reported to have traveled from Kansas City to Denver in a little more than 20 days. Upon the arrival of a wind wagon from Westport, Missouri, a Council Grove newspaper asked its readers: "Who says now that the Santa Fe Trail is not a navigable stream." The few wind wagons that were built undoubtedly traveled further in the press than they did on the prairie and horses and oxen remained the basic mode of power for a good many years.

“One of the more interesting sagas of Kansas wind wagoning came in 1860. Samuel Peppard, who owned a sawmill on the Grasshopper River near Oskaloosa completed his contraption. Built with assistance from John Hinton, it was dubbed by his neighbors, "Peppard's Folly." Later it was suggested that because 1860 was a year of extensive drought and business was slack, Peppard built his frigate as a means of whittling away idle time. Peppard, undoubtedly, had a more ulterior motive in mind as on completion of the craft, he and his companions set out immediately for the Colorado goldfields.

“A fairly detailed and entertaining account of Peppard's journey over the prairie sea can be found at the Kansas Historical Society. Although not identified by name Peppard received some national notoriety when a correspondent of Leslie's Illustrated Magazine reported the arrival of the wind-schooner at Fort Kearney. In the grand literary style of the day, the correspondent wrote:

“The ship (appeared) in sight about 8 o'clock in the morning with a fresh breeze from east, northeast. It was running down in a westerly direction for the fort, under full sail, across the green prairie. The guard, astonished at such a sight, reported the matter to the officer on duty, and we all turned out to view the phenomenon. Gallantly she sailed, and at a distance ...not unlike a ship at sea.  In front is & large coach lamp to travel by night when the wind is favorable ... A crank and band wheels allow it to be propelled by hand when wind and tide are against them.

“For some strange reason, no mention was made of the wind wagon episode in Peppard's obituary. While alive, however, he took pride in relating his experiences with the wind-wagon.

“Peppard's wind wagon was neither the first nor the last to traverse the Kansas prairie. From time to time there were other reports of wagons equipped to utilize the state's greatest natural resource as a propellant. In 1877 the Kansas Pacific used sails on handcars. As late as 1887 John B. Wornall of Westport carried a small group to a camp meeting. In 1910 it was reported that a sailing schooner had been invented in Louisville, Kentucky.”

Note:  There are other ways PCs and NPCs could use elementals as a source of clean energy.  A Wind Elemental forcing air into a Fire Elemental could create an effective blast furnace - smelting ores such as copper or iron.  This would reduce the cost of that metal per ton.  In turn, that would make the PCs that own an elemental powered blast furnace much money.

Nice. You're giving your players the moral dilemma of enslaving elementals vs "clean energy". What will they choose? 

I have a Sand Sea, and a "crazy old coot" who lives in it created a wheeled and slide mounted catamaran that has become a standard way to get around on it. Merchants use them much the same way that ferries and river barges are used.

They just use regular wind, but spells would work.  I suppose a good persuasion check could possible talk some kind of air elemental into helping out, but damn, I worry about what they would expect in return...

Quote from Rathkryn >>

Nice. You're giving your players the moral dilemma of enslaving elementals vs "clean energy". What will they choose? 

I mean, that assumes the Air Elementals used have humanoid analogous awareness and/or sapience. In the basic lore, your standard elemental doesn't really have either in its natural state; the forms players/characters are familiar with are basically just portions of the appropriate Plane drawn to the Material Plane and shaped into a particular form. Could just as easily present them as draft beasts or even just a volatile source of energy.

An Air Elemental has an intelligence of 6. So while it is not the smartest of creatures it is smarter than a draft horse with an intelligence of 2. Thus they do have some sort of sapience.

Of course if you don't want the moral dilemma you could bypass that with a non-sentient wind drawn from the Plane of Air akin to a decanter of endless water. 

There's also no reason the elemental might not enjoy the work. The fire elemental that powered my group's airship was basically a pet that would disembark with everyone else to go on adventures.

Quote from Rathkryn >>

An Air Elemental has an intelligence of 6. So while it is not the smartest of creatures it is smarter than a draft horse with an intelligence of 2. Thus they do have some sort of sapience.

Of course if you don't want the moral dilemma you could bypass that with a non-sentient wind drawn from the Plane of Air akin to a decanter of endless water. 

INT scores aren't a great metric for how a creature should function, really. Beholders, who per their descriptions are supposed to be ultimate villainous geniuses, have an INT of 17. A respectable score, certainly, but when a Mind Flayer has 19 INT without an accompanying fluff about their dizzying intellects, it rather undercuts the idea that you can get more than generalities from INT. Particularly when, again, you're dealing with something so removed from the humanoid frame of reference. An elemental is not a living being with the kind of basic drives any living creature has; it's the fundamental matter of another plane given a form by the magic of another being so it can function in the Material Plane.

I haven't done that much with Eberron but my understanding is that in that setting there are groups that have harnessed (some might say enslaved) elementals.

From the Monster Manual:

Living Elements. On its home plane, an elemental is a bodiless life force. Its dim consciousness manifests as a physical shape only when focused by the power of magic. A wild spirit of elemental force has no desire except to course through the element of its native plane. Like beasts of the Material Plane, these elemental spirits have no society or culture, and little sense of being.

So I'd say the Intelligence score is misleading. An air elemental powering a zoomamathing and going real fast in the open air is probably a pretty happy air elemental.

Peppard Wind Wagon

George Rolla Peppard sketched this drawing of a Peppard Wind Wagon. This innovation of the Kansas territorial period capitalized on an abundant natural resource, wind. In 1860 these wind wagons, sometimes called sailing wagons, received considerable attention in the press. Similar to an ordinary light wagon, they weighed about 350 pounds and had a bed about three feet wide, eight feet long, and six inches deep. A sail or sails raised over the center of the front axle propelled the wagons. When the wind blew in the right direction the wagons were reported to skim over the prairies at about 15 miles per hour, with speeds at up to 40 miles per hour.

An air elemental directly behind the sail or sails could double that speed to 80 miles per hour.  Powered by an air elemental means that the wind wagon could be built winder and longer, carrying more passengers and more cargo than a light wagon could.

In addition, while horses and mules need to stop for rest, drink water, and eat food; an air elemental can push a wind wagon 24/7.  After all, an air elemental has total immunity to exhaustion.

In Dungeons and Dragons, tools and weapons can have magical upgrades; therefore wheels could be magical as well.  Magically enhanced wheels give a smoother ride; give the driver more control over the vehicle, and a faster speed.  These magical wheels give these wagons an extra five miles per hour per plus one, with a maximum of +5 or 25 miles an hour for a maximum possible speed of 105 miles per hour.

If you think that is too fast for a cart to move; don’t forget that an air elemental can cause (3d8 + 2) damage.  Imagine what could happen if that amount of force was pushing against the sail or sails.

I love these wind wagons. I've never heard of them before.

Re: Eberron -- I have the 5e book. In there, they refer to the use of elementals in transport and industry as "binding." It's a magical effect that keeps an elemental in place. (The same word is also used to describe a moral and legal obligation certain people have to fight for a particular faction. Idk if that's relevant but it came up in my search.) I think the writers go out of their way to avoid setting in stone whether this is an act of cruelty, because they want you to decide for yourself.

Keith Baker, who I'm to understand created Eberron, seems to feel similarly. From his blog, "there's no easy answers in Eberron." Though, I will say, he devotes less time to the autonomy denied to elementals, than he does to the dangers of an elemental accidentally unleashed on society, as an argument for or against their emancipation. He also notes that some factions see their binding as an affront to the natural order, but again, this isn't really for the elementals' benefit.

I also have the 3e book, but it's more of a hassle to search it for mentions of the word elemental, so I'm not gonna.

Going to tell my players about this. Currently they have a wagon and no horses because they forget to care for them. So the 2 wizards cast Fantom steed in turns for traveling.

I read a ... like, a graphic novel, once, and in it 'landship' plied the hazardous desert lanes. These were not comparable to the sail wagons, they were literal rolling fortresses, sporting dozens upon dozens of sails, as well as (if memory serves) teams of draft animals. Lizards, I think. 

This was a long time ago - all I remember is that one picture of the landship.