Yes, it is. Unless you have an explanation of why not without getting into no true Scotsman territory.
Minimalism isn't the ideology that (less is more)==(less things). That comes from people appropriating philosophies to compete for attention on social media, where everything is at best one-dimensional because the point is to entertain not educate. No, minimalism as a philosophy means (less is more)==(object-essentialism). You initialize solutions among what you have, and factor the time, resource, and opportunity cost into the cost-benefit of acquiring a new object. So, as I mentioned, if acquiring a backyard of junk cars is more cost-benefit savvy than having to acquire a new junk car every time you need a resource from one, it's minimalist. However, if you acquire a junk car that adds what you already have a sufficient amount of, it's frivolity.
And frivolity isn't a relevant category to minimalism. You could be minimalist in achieving frivolous ends. Clearly you're carrying too much in the term.
Wikipedia has it as: "The term minimalist often colloquially refers to anything that is spare or stripped to its essentials."
Oxford Dictionary as: "a style of art, music or design that uses very simple ideas or a very small number of simple elements"
So in my opinion, having rusting car wrecks around in an old shed with the intent to re-use their essential spare parts later is perfectly compatible with minimalism, and what I would expect someone with the skill set and space to do so.
Contrast that with a large garage where numerous expensive cars are being parked and continuously maintained as well as cost of electricity, cleaning, security etc. for the building, although the cars are pretty much never driven.
That would be much closer to a minimalists nightmare. Not the self reliant utilitarian guy with the old shed.
The first is minimalist because it involves less physical material to store and organize. The second is self reliant because you can do for yourself without needing to draw on outside systems as much.
The example you gave is just moving the goal posts completely. The large many car garage case is both less minimalist and less self reliant, so not to the point.