The extreme waste of energy, space and other resources when we use a vehicle weighting 1.5 metric tons with space for five people plus luggage and often with off road capacity to transport one person a few kilometres along a good road.

An isetta would never pass current safety tests. Crash tests have to be passed with a certain investment in weight, and nothing smaller than maybe a smart or twizy can anymore.

If all cars in a city were limited to say 30-40kph and to a certain maximum weight it might be possible to limit the maximum kinetic energy in an accident and thus require less safety margins. You are not going to be able to take it out of the "safe zone" though.

And the solution is that people buy a second car that is capable of only hauling one, max two people in it?

And how does it even solve the space issue? You're not going to be making narrower lanes to fit more of these side by side.

The solution, except the more obvious ones bicycles and public transport, is that people that absolutely need a car for their daily commute don’t have more car than they need for that. Then when they need to haul something or go on a fishing trip twice a year they rent cars for that.

You would make narrower lanes if most cars looked like this. Not to talk about all the parking space you would save now already.

Why should I need to both own a car and rent a car? I'm not made out of money and I suspect I'm not at the bottom of the income pool. And I'm not going to get any kickback for the time that my car is sitting out there, not being driven.

This isn't even a matter of "going on a fishing trip twice a year". A bubble car is not enough of a car to go to IKEA or even an electronics retailer.

Because the car you’d own could be substantially cheaper than the car you currently own, making up for the entire difference for when you go to ikea or for an extended road trip. Delivery from ikea is entirely an option, too.

I doubt the depreciation, insurance and fuel are going to be that cheaper for it to become economically viable to pay an external company for a car.

It’s fairly common that people massively underestimate the actual costs of owning a car (let alone the externalized costs such as free parking and environmental effects), but several studies lately consistently put the costs at around 500EUR/month in europe. Here’s a little example: VW Golf, mid market model, 30k EUR new, monthly total costs ~600 EUR. https://www.adac.de/infotestrat/autodatenbank/autokosten/det...

I can rent a larger car for two weeks every month for that amount money.

Compare that to a Citroen C1 (still a 4 seater car that can go > 160km/h on the autobahn) 370 EUR: https://www.adac.de/infotestrat/autodatenbank/autokosten/det...

That’s a monthly difference of 230 EUR. That’s enough to rent the Golf for a full week every month. (I only did a cursory check at a single company, no discount etc: 233EUR/week)

Prices in the US may differ, but I doubt that the total economics play out substantially different, because that would imply that the market for rental cars would have serious potential for lowering prices.

Now think about the potential price difference if you could buy a vehicle that doesn’t need to go faster than 80km/h and was optimized for urban traffic.

Xylakant covered most of it. But just to add: when you want to haul furniture you rent a proper truck, and when you want to go on a fishing trip with your buddies you rent a nice 4 wheel SUV, and when you want to go on a cross country road trip you rent a nice sedan or even a cabriolet if that is what you want, instead of every day driving to work in a too big and expensive car that kind of works ok for all of the above.

Let's say that I need to go get a shelf from IKEA next weekend. Renting out the absolutely cheapest car (from Hertz) is 95 euro for a day. A larger one is 107 euro a day. If I wanted to for example get an automatic, that'd be 240 euro a day. 240 euros is already three months worth of insurance. And that's just for having a Ford Focus for 24 hours. And I need to drive to the airport and back in order to have the damn thing, so that's 50 minutes of driving on top of it. Hopefully they don't charge me to park there as well.

And for what purpose? So that I don't have the burden of owning a non-miniature car? I cannot fathom what the point in this exercise is. It's not like the miniature car has some immense superior qualities to it. By contrary, it seems to have an awful a lot of negatives.

How often do you really do that? Be honest, but very few people go to ikea and buy a single shelf every week. And for anything more than a shelf or two you’ll likely need a larger car anyways.

Why don’t you go to ikea, shop and drop it off with the folks offering transportation? They’ll take 40 or so and deliver a full minivan load for that. Or take a cab? There’s also car sharing options that offer minivans in many places for as low as 5EUR/hour.

Motorcycle and scooters are a thing.

Motorcycles and scooters are both a completely different class of vehicle.

Congestion.

Making a slightly smaller car doesn't do shit for congestion. Dumping a 100 Minis in a location is going to congest it about as much as 100 Maybachs.