Abarth became the wholly owned 'hot rod' arm of Fiat: the OTR was one of the number of race-focus Fiats that proved hugely successful around the world. As Cooper was to Mini, so Abarth was to Fiat. In 1965, Abarth launched the OTR 1000. OTR stands for Omologato Turismo Radiale meaning homologated (approved for International racing by the FIA), Touring (a closed roof car), and the radial pattern of the valve stems in the special hemi cylinder head. The OTR engine was based on an Abarth modified FIAT 850 block. It was the rarest member of Abarth's family of "OT" cars (OT, OTS and OTR 1000 Coupè) based on Fiat's mild-mannered 850 coupe. However, the SCCA thought the OTR was too modified and powerful for its class, and exercised its right to exclude from SCCA competition cars as “not considered suitable”. Abarth homologated the car in Group 4, not Group 3. The OTRs were meant to be Mini Cooper beaters and Porsche killers. While the European OTRs helped win Abarth all kinds of records and championships, the OTR never raced in America. Despite the fact that the FIA required 50 units for homologation, it is estimated that only round 35 of these OTRs were ever produced. (conceptcarz.com, hemmings.com, carsales.com.au & classicitaliancarsforsale.com)
(Photos from conceptcarz.com, carsales.com.au & classicitaliancarsforsale.com)