Light vehicles: What is?

[Liberty or Ded]

Okay so this question has come up before but the content of those threads is...well, useless.
I can't for the life of me figure out what light vehicles are. No, they are NOT the little green bars next to their health bar. How do I know this? Well, one of the vehicles I started out with had two green bars. Then after some upgrades, it had four. ...Now after a fight, it has three. Another vehicle, one that is DEFINITELY a light vehicle [it has one slot and it's tiny, it's the one that looks a bit like a dune buggy] started with one, but now it has two green bars next to its health. So, that's really not it. I dunno what those bars are for, but I really don't think they denote vehicle weight class.
I know some of the ones that are the more obvious light vehicles, but what I'm trying to determine where the line is drawn between weight classes.
Kinda wish there was something in the game or somewhere that lists the vehicles, their names, and their stats

[Zomboss]

I think, what green bars - it is defenetly weight. Light, medium, heavy, superheavy. And it define, who you can push out place (same or lighter). If you install melee weapon (like chainsaw), car get additional 1 weight point for every melee. It's only thing, what chenge weight, what i saw.

[DonVino]

it is about the green bars indeed
1-light
2-medium
3-heavy
4-extra (only achieved with chainsaws)
adding a chainsaw to a car adds +1 bar.
if you wanna go for the light vehicle achievement avoid chainsaws, do not equip them.Ever.

[Liberty or Ded]

Yeah, I figured that green bars WERE actually for it, and I didn't know why they shifted, but now I do! lol I got the achievement, lost two of my escorts and the others were torn to hell so I barely scraped by, but I won and that's all that matters. lol

[DonVino]

main truck with 4 lasers helps a lot ^^

[Liberty or Ded]

I tend to go with four railguns; even the battleship on hard's pilot deck won't survive a single volley from all four railguns. Or two railguns, a leech drone, and a shield, if I can get those. That's the "Solo MCV" setup right there, especially on the high-evasion MCV.