I've always heard it called a 'rabbit' [1], but I like 'sacrifficial jerk' and will probably use that from now on.

1. http://radartest.com/Top-5-Tips.asp

My term for this is "minesweeper"

We call this guy "lightning rod". Interesting how we've all identified this actor with different but essentially synonymous terms.

We always called this guy the 'red herring', to throw off cops.

We call it a horse in Lithuanian, because it's always in front of the carriage.

And no, we don't use horses anymore.

We called them designated decoys where I grew up.

One thing to remember is many cops will grab the car nearest to them instead. It happened to me when I was matching pace of traffic while speedometer went out. I was in the back. Cop pulled me over instead of the speeding leader.

Exactly... or they can direct you to pull off the road and then get the others and you just have to wait there.