Update: So apparently it remembers the green colour fine for some reason. I don't really care that much though since it matches the stock cluster the most. Its been working fine, and it hasn't been overly gentle weather so thats a plus. Its been like super mega cold here a few times, and its been fine. I've noticed that the needle can be a bit jumpy at times when its moving but overall its smooth and ok.
As for the gauge itself, well. Shipped to me it was like $50 so I can't really complain there, but I'm honestly not that impressed. The colour changing would be nice if it could remember all the colours, but since it only remembers the default blue or green its a let down. The constant is fine, otherwise it wouldn't remember the green. At night the gauge is easy to read and the colour is bright enough to be easily readable, but not too bright to blind. During the day though its balls. Like I'm lucky if I can make out the numbers on the far left. Right side is a joke. I do have a sunroof, but given the location of the pillar it isn't affected by the roof being open or closed (with sunshade). I would recommend a white-faced version of this gauge instead. It would also be nice to be able to have a harness on the back of the gauge for easy removal too.
I'd give the gauge a 6/10.
I have noticed my fuel economy getting better though, but that may be because I switched to the INST MPG DIC readout. Easier to know when I need to let off. The gauge helps a bit too though, but more with throttle control than anything.
2008 Cobalt LT // 2.2L Supercharged w/3.1 GM stage 2 pulley