I used an AiM SoloDL and a SmartyCam on my Fiesta
http://www.m-world.us/aim_solo_dl_gps_lap_timer_data_logger.html#aim_solo_dl
I have not autocrossed my Fiesta ST yet.
http://www.m-world.us/aim_solo_dl_gps_lap_timer_data_logger.html#aim_solo_dl