As a car enthusiast, I can think of a good one, the Ford Nucleon.
During the 1950s and 1960s, there was considerable interest in nuclear power and its potential applications. This led to the idea of using nuclear energy to propel cars. The concept behind a nuclear car was to utilize a small nuclear reactor to generate steam, which would then power the vehicle's engine.
Of course back in those days, this was extremely futurustic and some at the time thought this would be a game changer, but ultimately, the safety aspect was one of the biggest reasons why this idea was dropped, and I probably don't have to explain why it may not have considered to be safe, I mean, it was using nuclear power, so even if the engineers tried to make it as safe as possible, IF something went wrong, it would have been catastrophic.
Ever since then, the interests in the automotive sector has shifted to Electric and Hydrogen.
Still, a very intriguing concept car and idea.
Outside cars, you have blimps, and I personally believe if we tried to make something like a hindenburg today with existing technology, we might have been a lot more successful than back then (as it goes way back to 1930s), there are still some blimps used occasionally, I also don't believe those use hydrogen(?), but they are not the "game changer in air travel" it was once seen as, although we can't rule out a comeback.
What about you guys?
The one flop that sticks in my mind the most was "IT". "IT" was going to revolutionize the world, nothing would be different, it would make each person richer than Bill Gates, and so on.
"IT" was the Segway. It was a two-wheeled vehicle that could go a max speed of 12 MPH/19 KPH for a distance of 25 miles/40 km and it cost Twelve Thousand Dollars. Know what else balances on two wheels and goes 12mph? A bicycle. And I can pick that up for a few hundred bucks depending on what I want. At the time, you could buy a very nice motorcycle for $12,000 and it would go much farther than 25 miles and considerably faster than 12 mph.
As someone who was born after the whole Segway fiasco but has heard about its apparent crazy marketing, is there a QRD on what exactly made it so unwlderwelming? Or some kind of video that made the Segway's release as infamous as it is? I've seen this answer a lot in these kinds of threads
The segway itself could've lived up to the hype.... If it were as affordable as a vespa! it could have taken over that non-highway travel niche but it cost 10 times as much and had less range. The hype was tone deaf to the average person's disposable income. You can't revolutionize the world if only independently wealthy people can afford your toy. I'm sure that wealthy tech bro ceo was very out of touch with working Americans wages. Later he died by driving off a cliff on a segway.
You see them and their successors now in crowded pedestrian spaces (often for security guards) and it's arguably less intrusive than a skater but with long distance potential. That said I think the monowheel electric skateboards are the best thing for that now and not nearly as expensive.