The red segment at the bottom of the fuel guage should light up as brightly as the other segments on the temp guage and rev counter. The low fuel warning light is in with the other warning lights to the left of the main guages.
Mine used to work but went out some time ago. Due to my travels I didn't get around to asking my local dealer about it.
My car went in for it's 2nd service yesterday (Thurs 28 Feb) so I went into the dealer last Saturday to tell them about a couple of issues.
I figured they'd then have 5 days to investigate and order any parts they needed.
My CD was constantly skipping and they were able to order in a replacement head unit, so at least that was worthwhile....

As for the fuel guage.... they were unable to confirm whether it's a bulb or an LED and told me that I would have to book the car back in so they can take the dash out and look.
Of course, despite being a main dealer that always has Crossfires in stock; they don't even have a workshop manual....
If it's a bulb it's not covered by the warranty. I asked them if it was covered by warranty if it were an LED unit. They couldn't even confirm that, saying they they would have to contact Chrysler to check. You don't even want to know how much labour they were going to charge me to take the dash out to look.....

As an aside, there is also a rattle coming from the front somewhere: I think there's a loose screw behind the internal trim... they of course couldn't replicate the problem and told me it was stuff in my glovebox (which I had emptied)...

At least the actual service went ok (I think)....