You just tickled my nostalgia. I remember those arguments.  

 

how about just the panels in general. If bumblebees hood is splitting all those different ways, how is it even stable enough to open. Or the gas in the tank, is it in his gut? Cuz it seems like having a bunch of fuel inside of you is not a good idea for battle.

 

Well, its probably been mentioned, but they are just scanned disguises. The windows are no more glass than the tyres are rubber. Everything on a TF is mimicked and not the real material/item.
They don't just crawl into an existing shell and build it around themselves as a disguise, they scan an object and mimic it. All materials are replaced with space age material and alien metals.
So, the windscreens could presumably fold up or slide away I would imagine.
Plus, after a battle, they'd never be able to TF ever again without seeing 'Joe the Panel beater' all the time if this wasn't the case. They have to be made or stearner stuff to withstand the punishment they get.

 

I don't think they work on gas when in alt mode. Rather like Mystic Space Power or smth.

 

Although if they want to have really good disguises they'd probably have replicate having fuel in the tank. I suppose you could say why would anyone be looking in the tank to actually see the fuel, but if you were driving a car and it still hadn't run out of fuel after 5000 miles you'd be wondering what was up. Or were just really happy you'd found a magic car which didn't run on petrol considering prices these days.  
I guess if these TF really do have nanobots in them those could pretend to be petrol if someone really wanted to look. Just have to hope no-one then siphoned the 'fuel' out.
Going the other way though, what if someone was driving a disguised TF without knowing it and filled the petrol tank up. And then the TF had to transform for battle. They'd be a walking explosion. Not that Michael Bay would mind.  

Seems like a whole life ago, don't it?

 

I think it would just... trickle out or something, because I don't think the tank stays in one piece when transforming.

 

Don't - you'll have Bay making the TFs wear 'giant f**king nappies' in the next film.  

Maybe the nanobots would just convert the fuel and make it safe. Or convert it into some other useful liquid, probably to be squirted on Simmons.