Road and Track has listed and written short blurbs on every Ford RS model. All those models have led up to the release of our friend the Focus RS. I have to say that the list is a lot more lengthy than I had thought.
I posted a few of the ones that stood out to me below, but the whole list can be found through the link here --> http://www.roadandtrack.com/car-culture/news/g6489/every-ford-rs-model-ever-made/
1970 Ford Capri RS2600
1975 Ford Escort RS1800Having debuted at the 1970 Swiss motor show, production of the lightweight Capri RS2600 was limited to 50 units to meet homologation requirements. Production of the streetable RS2600 started later in the year, and it was the first Ford vehicle in Europe to employ fuel injection. In 1971, Ford would sell regular Capris in the U.S as the Mercury Capri.
Production of the Mark I Escort ended in December of 1974, and the first Mark II Escort to receive the RS treatment was the 115-hp RS1800.(Competition version pictured)