When passing a person on the highway and they speed up to match your speed, staying with you until you brake of get ahead of them, at which point they slow back down to their original speed.
by Amarak July 21, 2009
A speed leech is a person who leeches speed off another driver when they pass. For example, one car is going a steady 50 mph and you pass him going 70 mph (because they are going too slow),..............and then "magically" they suddenly speed up to match your speed of 70 mph and keep up with you now , effectively leeching off your speed. This is done presumably because the speed leech figures if a police car is up ahead, the person in front will get the ticket. These people are cowardly people who are too wimpy to speed on their own and need to leech off another drivers speed
by Picaboshouse March 10, 2016