If one reads reviews of the sixth generation, the reviewers are quite pleased with the dashboard. They make a big deal about how the instrument panel is similar to the ones in the Silverado, the Corvette, and the Camaro.

Until we get to 2006.

Does anyone know why they dropped the cluster down to four gauges? I understand perfectly about decontenting, but the money saved by eliminating two stepper motors was probably spent by not only designing a new four-gauge cluster, but the black overlay in front of it.

 

not to mention the same cluster works in 06 and up impalas

 

I'm guessing it was consumer feedback that some felt the extra instrumentation on modern cars was a bit excessive (granted, I like the additional information).
May also be that the SS Monte and Impala did not have a long lifespan left (perhaps they saw that ahead of time) and decided not to put the money into a more feature rich cluster.
Keep in mind, crossing 05 into the restyled 06 (which we call the 7th gen), the computer electronics changed. I believe it was now CANbus/GM LAN (not the same ODB-II). This meant R&D to build a feature rich cluster on a car they may have already had it's end planned. Couple that with I believe that was around the era GM was in some of it's worst financial issues and looking to the government for a bail out, so it was all cost cutting.

To provide an example, looking at the Grand Ams. I had an '02 Grand Am GT and now my daily is an '04 Grand Am GT SC/T. On my '02 when you would set your cruise control, a nice light on the cluster would light with the word "Cruise". In '04, GM got rid of the LED and resistor to allow that indicator to work (with some help, I got that resurrected on my '04, it annoyed me not to have it). On the '99-'03 Grand Ams, to reset the oil life monitor, there was a nice reset button in the driver side fuse panel. In '04, no button (because the alternative method annoys me, I figured out how to wire a button in and now have that feature back too).
All seem a little petty, but it was all about cutting costs.

 

That's more information than I had before, so thanks. But it brings up more questions. If they were in such financial straits, why change the electronics from OBDII? Why not just leave the guts the same, and then carry over the same cluster?

 

That is tough to answer. My guess is that since the Monte was undergoing a re-style, they wanted it to keep up with the direction of the other cars. It is still ODB-II, but I believe it uses a different protocol. And part of that is probably to reduce parts they have to build for the cars (if they kept the Monte behind, then they would need old tech that they are phasing out).
Again, hard to say exactly why they did what they did.