I am making a CARS cake. I have made my red and black. My question is: when I let it sit over night how much redder will it get? Is this a good red for the car? Does the cornstarch make it lighter while kneading? I know I need cornstarch to prevent it from sticking to the counter but it seems to lighten it up when I add red or black.

Thanks for your help!!!!

Depending on what you used for the coloring, it might get redder overnight. Ive seen it with the Wilton gel colors.
The cornstarch shouldnt change the color any unless your adding a ton of it which is only going to dry it out. You can always rub crisco on the cake after your done and it will get a sheen to it and eventually soke up the crisco to reveal the color without a chalky finish from the cornstarch.

yes, I am using the Wilton coloring paste. I wondered about the cornstarch drying it out as well. I only add a little when it starts to feel sticky! Thanks for replying!!

Yah, Wilton colors have a tendency of getting darker the longer they sit.
If you put your cornstarch in a little cheesecloth sache' thingy, it will limit how much goes on the fondant. But if it seems like its getting dry, add some crisco to it and knead it in. And like I said about the dust of it, you can do the same thing.