[ChevyGuy]

So I guess the question is, which of the two in this domestic GM car is the most accurate one?

I think it's safe to say that the digital display is the better reflection of what the car's computer wants to show you. To determine which is more accurate, you'd have to have some kind of outside measurement, such as a timed measured mile to know for sure.

Note that the error in the analog gauge is only about the width of the needle. And that can vary depending on the angle you're looking at the gauge.