There seems to be a culture of knocking down other people's ideas and jumping in to side track a post before there is much opportunity for constructive criticism on the eplaya. I wouldn't let a bunch of negative ninnies online shut you down or force you into a stage of redevelopment and self doubting at the refinancing that would come out of it, because frankly, it's your idea and the fact you have a team together is pretty dandy. Of all the people who said it would never get approved by the DMV, do any of you do that? Have you run a vehicle by the DMV before, because it seems like you spend a lot of time posting about other people's ideas online and I question if you have the time?
It seems like there's a few genera of common ideas, just to name a few more common ones I saw at the burn this year, there's steam punk, fluffy / garden / cute / animalish / easterish things, common monsters and common mythos. ...and while I didn't see a lot of apocalypic stuff, I bet it was out there, and has been there. But, just like the fluffy bunnies and the cool train steam punk city things, they all got there too, and honestly, the majority amused me in some capacity. (some more than others, pink fuzzy things just don't do much for me) There are some epic art cars out there too, which are HUGE! Like a gigantic dragon, a space ship or a love potion moving party! Some are epic for their creativity, some are epic because they can take tons of people with them or have fantastic DJs set up on them. My point is that you don't have to become epic because you thought of a genera that nobody else did - even of the epic cars I just named, Love Potion is the only one that seems truly unique. Maybe people like things they're a little familiar to?
Now, your idea-
Utilitarian- I love the utilitarian aspect of it. I'm a utilitarian myself and generally anything utilitarian makes me happy. The digger ma-gigger sounds really complicated to set up and to balance, plus, I'd be terrified to drive it around with the drunks and dark people dancing in front of you - it's one thing to hit someone with a blunt object, but a pokey one, that's just wrong. When would you use it anyway? Perhaps there are more utilitarian functions that one would need out on the playa, the Wasteland, etc. What about a tow system? Perhaps it would be better to think on things that would aide in the bounty hunting...
Hammock - Nice. I have an amusing idea of setting up a whole slew of hammocks and having people sleeping from all over it, but I don't think that was your intention, still, I like it.
The Turrets - Does anybody get to shoot those? How do you control passengers using them vs crew? Will the fire one get hot, and with people strapped on all over the place, will it be an issue?
Guns - I didn't see a lot of guns on the playa, with the exception of a single Dalek with a laser-arm-thing. Maybe I don't notice them, and I don't know the rules on them, they're not my thing. I brought it up because it is a big apocalypse thing, so - perhaps some research into weapons rules would be ideal?
Characters: I'm not sure if this was intended, but I like that in my head, the hot chick on the hood (HCOTH) was dancing in a CAGE, so she was kinda like post-apocalyptic property.
HCOTH's Picture (AHEM! THE PICTURE OF THE ART CAR!!!) - She has nice legs, but the hood thing looks more like a place to cook bacon. I like how you welded pieces of metal together there, but I would like it more if it happened less evenly. If you read the Preparing for the Wasteland" documentation, one comment they make about costumes is that you should look like you have "limited resources." That, to me, means more re-purposing and less things fitting so well. This also means things got really damaged and you're using them anyway. Ultimately, it means I get to play with a blow torch in my back yard and wildly mix hazardous chemicals and pour my concoction over things to accelerate the annihilation process!
When you say lights, I presume you mean the big deer hunting ones. We used to cover them with electrical tape to make them look like they were broken, while still getting a lot of light out of them. You may be able to make some metal light filters / shapers to put over the lights so they do not blind people like they do deer and make them more cool.
GanGRENE - That's a cool name, quite unique.
Using it - Have you considered going to the Doo Dah parade? Also, I'll see you at the wasteland, if you need any help, my sister and I will be in a faded partially copper roofed yurt that is missing chunks of the walls and is strapped to a scratched Honda Element with a cracked windshield.