Well, yeah. They're spree killers.
But psychologically, I think they had more in common with mass shooters such as Harris/Klebold than with, say, your typical Ted Bundy or Jeffrey Dahmer type of serial killer. Given that this was an "extinction burst" with no "cooling-off period," rather than something where they resumed normal life between killings.
I mean, it would be really easy to conceal a body in that area -- or a vehicle, for that matter -- and have it not be found for a long time, if ever, and get away with it. But that wasn't what they did. In fact, some of their actions could debatably be interpreted as drawing attention to what they did and where they were going, but just enough so the police were one step behind. Almost like they were trolling the police. How long would it have taken the police to figure out where they went if they had rolled the car into the bush, rather than setting it on fire and guaranteeing it was immediately found? They even left a trail of scattered items leading to their dead bodies.
And especially, given their whole "militia of two" image. They were basically "pseudocommando" killers, as it is termed in criminology, and those type of killers are usually mass shooters. As far as I know there haven't been any "pseudocommando" serial killers, although I could be wrong.
Like, let's put it this way, if I had to guess who they were inspired by, I'd say mass shooters (and probably ones who were around their age), not serial killers.
But yes, their methodology was very uncommon, which is what makes this case so weird. Especially the fact that they stopped killing. Can anyone think of any case similar to this one in terms of methodology?
I don't think the vehicle troubles had to do with what they did. I also don't think they planned to get away with it. I think they left knowing this would be a suicide mission. They didn't seem bothered at all by the prospect of killing themselves, going by the description of the videos, which indicates to me they went into it knowing that's how it ultimately would end. I think they saw it as a video game sort of thing, where they would try to evade police as long as they could, but knew at some point it would be game over.