Hey. This post is going to be just sort of a summary of possible solutions to your portable oxygen problem, starting with what is simply a direct answer to your question, "Can I run an O2 concentrator on a power inverter in my car?"The answer to that question is likely, "Yes." And in a post, yesterday, I kind of summarized how that works. It is an electrical power problem. I suggested putting a power meter on your O2 concentrator, as sort of a first step, to get an accurate estimate of the amount of power your machine wants. Then from there, you can start thinking about how big, in terms of rated power (500 W? 1000 W?) of an inverter is actually needed, and how many amperes this will draw from the car's alternator, and wire sizing (what AWG size) for wire connecting the alternator to the inverter.Also if the current draw really is like 40 A continuous, you might need a bigger (higher current rating) alternator, but I am hoping you won't. I am hopeful that the time averaged current draw would be something much less, but the only way to find out, is to get some reliable numbers for the real power use, by measuring it, with a power meter.So I think that is a good answer to, "Can I run an O2 concentrator on a power inverter in my car?"However the actual underlying problem, as I understand it, is something more along the lines of, "How can I provide myself with medical oxygen, while stuck in my car, for a time duration as long as 20 hours, in a slow moving ((300 miles)/(20 hours)=15 mph average) traffic jam?" And it is that implied question that kind of maybe points to other, more exotic solutions, of which I have discovered just two, so far.One is cryogenic liquid oxygen, which I thought was mostly the domain of like rocket ships and rocket scientists, but it turns out the medical industry actually sells, and distributes, this stuff too. It begs the question, well, where's the nearest place to refill a LO2 cryo-container? Is it as easy as, asking Google(r) Maps about "liquid oxygen refill near me"?https://www.google.com/maps/search/liquid+oxygen+r...I dunno. Somehow my intuition tells me that if an actual evacuation order was given, that time would be better spent driving out of town, than driving to the place that refills the LO2.The second possible solution, that is out there, but maybe not well known, are portable chemical oxygen generators. The advantage of these, is that they can be stored, inert, for years, but when activated there is this kind of exothermic... I mean, hot, smoldering, reaction that makes usable oxygen in large volumes. https://en.wikipedia.org/wiki/Chemical_oxygen_gene...I knew they had these things on commercial airplanes, and also space stations,https://www.instructables.com/answers/How-the-oxyg...But just for the sake of finding what else is out there, I decided to ask Google about "portable chemical oxygen generator", and one of the results that came up, that was an actual product, and not just a patent,http://www.o2pak.com/specs/and it would probably be a good deal for you if they sold them cheap, in a 48-pack, because I am guessing each one would last you about 0.5 hours.(Of course, state-of-the-art, medtech gizmos like this, are usually NOT sold cheap.)For some reason, the physical appearance of one of these things is superficially similar to a can of beer. Or that's the way it looks to me. The procedure for activating one, looks similar too. You should watch some of their Youtube videos, e.g.Or maybe the resemblance to a can of beer is me thinking that because I am totally out of beer. I am curious to know if this gizmo reminds anyone else of beer.Anyway, that's all I have got for now, regarding other car-portable, medical oxygen solutions. There may be other things out there to discover, if you just search for them.