Flying cars will always be less efficient (and thus, more expensive) than driving cars due to the physics of it. I wouldn't hold my breath on flying cars replacing driving cars, just as airplanes haven't replaced trains.

> Flying cars will always be less efficient (and thus, more expensive) than driving cars due to the physics of it.

As it stands, for cars, the typical energy use is 3k-4k BTU per passenger mile. Commercial airliners use 2k-3k BTU per passenger mile. Of course those get their efficiency from packing more passengers in. But the point being that a statement like the above only makes sense when comparing comparable vehicles (the bad numbers for cars is in part because cars on average have less than 2 people in them; fill a car up, and it will do better per person than a typical plane).

However the best reported numbers I've found from test flights of electric planes is energy use as low as below 1300 BTU per mile (these numbers will also vary wildly by number of people; most prototype models in progress are for 2 people, including Lilium, though their next version will be a five seater).

Part of this is due to totally different design constraints. Of the 12 in-progress models I'm aware of, the heaviest is about 1/4th the weight of the lightest Tesla. The lightest is about 1/6th the weight of the lightest Tesla. E.g. the two-person version of the Lilium was 400kg without passengers.

Part of this again is that the cost of purchase vs. cost of operation calculations are entirely different: Most of these are designed for the hire operator market or as luxury items, and they're not even possible if they weigh too much, so much more money gets spent on expensive materials to push weight down. Their assumption is that they'll get the operational costs down far enough to amortise the increased finance costs of buying it.

Yes. The Uber Elevare white paper looks at this issue, and the stylised numbers are:

Car: 1 mile/kWh

Flying car: 2 mile/kWh

Electric car: 3 mile/kWh

(Electric engines are much more efficient than combustion engines.)

So, it’s not too bad, plus ground based vehicles (according to the same study) have to drive on average 1.4 miles for 1 mile distance “as the crow flies”.

However, the numbers above are for fixed wing flight, as far as I can tell. Drone-like hovering flight is less efficient.

Still, I think that’s not the main problem. Regulation, battery specific energy, ATC are bigger hurdles.

https://www.uber.com/elevate.pdf/

We've had 'flying cars' for 100+ years already, and automobiles are still around. Flying just doesn't make sense (energy, safety, and practicality-wise) compared to rolling.

We haven't though. The distinction between these aircraft and typical planes being that they don't need a runway (several of them are VTOL), and are aiming to do away with the need for a pilot. The big limiting factor for small planes have been that combination of cost, inconvenience (nearest airfield to me is far enough away to make it pointless, and most places I'd want to go to don't have an airfield nearby either), and the need for a pilot.

First when you solve all three of those, you have something that is addressing the same market.

We will see whether or not it will make sense - there's now half a dozen manufacturers at least that claims to have electric aircraft in this class that are efficient enough to be comparable with electric cars in energy use. Of course it's possible they're all wrong.

> there's now half a dozen manufacturers at least that claims to have electric aircraft in this class that are efficient enough to be comparable with electric cars in energy use.

You'd have to use a very loose concept of “comparable” for such claims to be plausible, but the personal flying vehicle market has been rife with vaporware draining the wallets of investors and enthusiasts (the latter through early sales of reservations for “imminent” models) long before “electric” was part of the usual pitch.

> You'd have to use a very loose concept of “comparable” for such claims to be plausible

There are actual flying prototypes that have gotten at least within a factor of two of electric cars, depending on respective passenger loads. How they'll come out with production models remains to be seen, and also depends greatly on average passenger counts.

People tend to overestimate how much energy flight takes - consider that both large scale commercial jets and small private aircraft are relatively comparable to cars in energy use per passenger mile, often coming out better for larger planes than cars (though admittedly largely because average passenger numbers for cars is so low).

> but the personal flying vehicle market has been rife with vaporware draining the wallets of investors and enthusiasts (the latter through early sales of reservations for “imminent” models) long before “electric” was part of the usual pitch.

That's true, and I got a good laugh of e.g. seeing a pitch from a company in this space that included the Moller SkyCar as a competitor (I'm not sure if they were serious and included it for completeness, or if it was in there as a joke; they included the year it was announced, and that it was not yet available, I'm presuming it was a joke), but there are a few significant differences: The rapidly improving energy density for batteries coupled with much simpler designs and more advanced materials allowing for lighter planes. Add in autonomous operation and the cost picture for operations changes dramatically. This to me is the biggest change: Several of them are now aiming for "Uber in the skies" rather than selling to individuals, which allows for entirely different financial tradeoffs.

At this point there are also multiple flying prototypes, which is a marked difference.

> There are actual flying prototypes that have gotten at least within a factor of two of electric cars

Linky?

> People tend to overestimate how much energy flight takes

But underestimate how much energy convenient VTOL takes.

> Linky?

This is one of the easiest accessible ones: https://www.theatlantic.com/sponsored/thomson-reuters-why-20...

> During a 62-mile stretch of its historic flight, the plane used about 25 kilowatts of electricity for a total energy cost of just over $3, according to its pilot, Klaus Ohlmann. In all, the e-Genius consumed just a fifth of the energy of a typical, fuel-powered two-seater airplane.

..

I can't share the rest I have unfortunately, as while the information itself is public (I believe the source is a study by Deloitte), the document I have also contains information that is not, and I don't have a publicly available reference for the source. I'll see if I can find one.

> But underestimate how much energy convenient VTOL takes.

I don't think so. E.g. Lilium uses VTOL, but the wings (holding the electric engines) starts tilting as quickly is possible to start taking advantage of ground-effect, as everyone is of course aware that VTOL is expensive. While the power they need for that short period of time is higher than ideal, it still ends up being a negligible portion of total power consumption other than for extremely short hops.