Well anyone who knows this for sure may certainly chime in.
That last car I had-that didnt have a temp gauge-was a 95 Dodge Spirit. (It did have an OBDII ECM). It ran hot on me one time when my water pump failed. Anyway when the water temp went to (according to Dodge 230° F) I heard a very loud mans voice over the radio telling me "Your engine is running hot". incidentely that warning happened BEFORE the idiot light came on.
Now does anyone know for sure "either way" if our Sonics will do the same thing?
BTW a gauge is the very reason I blew up my old Metro that I had years ago. I had just got off work after working 72 hours that week, and was headed to the campground (where my family was already-we had a seasonal site with camper hooked up all the time), anyway I was sleepy tired, and was literally watching the road in front of me till I noticed a boatload of steam coming from my hood cracks. The temp gauge was buried HOT. A warning over the speakers would have saved me that day. Even a light could have caught my eye. But that gauge had never ever went over the 1/2 way mark since the car was new. So I sorta quit watching it very much.
Now Im not trying to justify the light. However a verbal warning, a light, AND a gauge would be nice, and cost GM maybe a few cents more. I bet less than $10 Incidentely I too do like the gauges, especially if they actually do fluctuate according to real temps, but a dead gauge is worthless. And a verbal warning is always real nice regardless of gauge package, give me a verbal warning IN ADDITION.