I've just started playing this today, I definitely agree it's something special - the very low agent amount at the start of the game has really changed things around a lot as well as all of the other tweaks and changes. I really love the idea of starting from just a car and working your way up from there whilst scrounging up tech and resources. Cultists being melee orientated means I'm more willing to task risks with stun guns and stuff. Those ninjas are a pain in the ass though, right now I have no way to really deal with their throwing knifes.
About the mudranger; I can see why it's so limited since the early game feels balanced towards lower levels of tech and stuff but I think it should at least be able to travel across America. I had it in the centre and couldn't reach the west coast IIRC. The other problem (which I'm sure is more geared towards OpenXcom devs than you) is that there's no simple way of telling if your craft has enough fuel to reach a place or not.
Other than that I'm really enjoying the mod, raiding cultists outposts with body-armour and black market guns feels really damn awesome