The RABDe 12/12 was a three-car electric multiple unit that was designed with traction motors on all twelve axles to increase acceleration. It was introduced in 1967 to create a half-hourly service on the eastern coast of Lake Zurich. It was named “Mirage” after the Dassault Mirage III fighter jets delivered to the Swiss Air Force at the same time. Since the eastern coast of Lake Zurich is also being called “Golden Coast”, it got the second nickname “Golden Coast Express”.

Up to four sets could operate in multiple and usually, two were used together to increase capacity. From 1996, they were modernized and now designated RABDe 510. At this time, they were operated on other lines than originally. Soon, it became clear that their narrow doors required halts which were too long for the requirements for the S-Bahn Zurich. They were replaced by RABe 514 double-decker EMUs and withdrawn by 2008. By 2010, all had been scrapped.