I shot the Canadian today at noon. It had two unrefurbished units, now a rarity, with a dead-heading diner (Emerald).
I had the circular polarizer on my camera while I was shooting. Just for kicks, I decided to take it off and shoot the last few cars without it for comparison.
Here's the last car I shot with the polarizer ON, Bliss Manor.
Here is Elgin Manor without the polarizer.
Neither picture was processed in any way except to crop to size, and both were sharpened to the same degree.
You can see how the sky is darker with the polarizer, and some cloud detail is visible that is washed out without the polarizer.
What do you think? Is the difference significant enough?