Funny you should ask. Yes. 3 months ago.

Seriously, if you watch cement after it is poured and is wet, it is a
geyish green color. And as it continues to cure, the green cast
disappears, but it is there to start.

Bob, cement is not poured. Concrete is poured. But anyway....

I know that blue & yellow make green, and there is a little of both
in most grays. But the Kato cars were -GREEN-. No one except a very
seriously colorblind person would say they were anything else. They
are green under all the usual light conditions -- indoor, cool, hot,
outdoors, flourescent, you name it. This color cannot be mistaken
for a "greenish gray". Think "Weyerhaeuser" green.

Tim O.