It's a small metal compartment on the dashboard of most vehicles, with a flip-up glass case. A red button activates the teleportation technology and returns the driver to the Acceledrome.
It wasn’t until after the Lava Realm that Tezla added the E.D.R. devices to all cars in the Acceledrome, now having the confidence that humanity can defeat the Racing Drones. While its initial purpose was to safely return the drivers back to the Acceledrome, unofficially it was installed to prevent the Drones from taking any of the drivers' already-won Accelechargers.
It is revealed that the Silencerz also have E.D.R.'s of their own, and can immediately return to their headquarters with their car.
Since most of the vehicles of the Metal Maniacs and Teku only had one driver in them when in the Racing Realms, Dr. Tezla never considered the possibility for the E.D.R. being used for both drivers and passengers safely, Porkchop and Monkey proved that the E.D.R. was usable for 2 people in one vehicle when Porkchop drove his Nitrox 3.5-filled Old Smokey into the Junk Realm to crash it into one of the Racing Drones Sweepers and rescue Markie, Tork, and Taro.
Later in the Racing Drone Headquarters, the drivers used it to leave after saving Mark Wylde from the Racing Drones; where Monkey and Shirako Takamoto piggybacked on Porkchop‘s E.D.R. due to their own cars being destroyed.
When Vert was taken captive by the Silencerz, he told Sparky to use the E.D.R. to escape and get help from the others, Sparky emerged on Highway 35 where he was found by the others. It probably means that the default location where the E.D.R. teleports the driver (when there are no holograms of the Wheel Of Power) is at Highway 35.