Europe is on the brink of putting "Intelligent Speed Assist" technology on all new cars to slow drivers down to local limits — and even some U.S. states are hoping to follow suit. But the minute "speed governors" get mentioned, tempers flare, and it could make the movement to throttle U.S. drivers a challenging fight to win.  Today on The Brake, we asked mobility researcher David Zipper to give us a breakdown of the most common speed-limiting technologies available today, and to share how he responds to six of the most common concerns about them — from the valid to the downright silly.  Read more of David's past writings on this topic here and here, and check out the highlights of our conversation on usa.streetsblog.org.