The Supersport was a limited edition of around 3000 used as a styling exercise to gauge public reaction prior to the launch of the XR2. It was based on the 1300S, and included the bodykit and spotlamps that were to be used on the XR2, along with 13" RS 4-spoke alloys similar in style to those that were used on the RS2000 and some other Fords, and unique 2-tone side stripes. Unlike the XR2, the car used the same square headlamps as other Fiestas. The car went on sale around late 1980/early 1981 up until the XR2 was launched in late 1981.
It used the same 66bhp engine as the 1300S, but had more substantial driveshafts and dampers to cope with the wider tyres. It also had a bulge in the rear valance, as on the XR2, to accomodate the larger spare wheel.
On the inside, the interior was basically the same as the 1300S interior except for the Ghia-style seats, which were trimmed in either Red or Grey tartan fabric (which was actually called Carla, and doesn't look as bad as it sounds!)
The Supersport was available in Black, Red, Silver or White with a choice of Red or Grey stripes. There were also 2 option packs available. The Climate Control pack had tinted glass, a tinted band across the top of the windscreen and opening quarterlights. The Executive pack had headlamp washers, a sunroof and a radio/cassette player instead of the standard radio.
About 950 Supersports are still believed to be on the road. Original examples are now getting thin on the ground.
The webpage below has a few pictures of Supersports of varying colours:
http://www.interford.co.uk/forums/showthread.php?threadid=36738