The MX-5 Cup race cars start as complete MX-5 road cars from the Mazda Hiroshima, Japan factory before being transported to engineering development partner Flis Performance in Daytona Beach, Florida, where they are transformed into a race car. The series entered a sanctioning agreement with IMSA beginning with the 2021 season. Defunct series These are the series that were formerly run by the IMSA organization. IMSA GT Championship American Le Mans Series IMSA IS The International Sedan Series was short-lived and the genesis of the Radial Sedan Series. It is unclear if the 1969 inaugural IMSA Sedan race held at the Talladega Superspeedway Road Course was designated International Sedan Series or not. That being the only race held in 1969 details are sketchy, but over the winter of 1969–70 rules were officially promulgated for this Series. It was initially to be known as the International 100 Series as it was intended for sedans up to 100 c.i or 1600 cc., however was revised prior to the start of the 1970 season to include larger engines and presumably the name change to International Sedan Series. The next year, 1971, the Series was revamped and became the Radial Sedan Series with the revolutionary innovation of requiring DOT radial tires. New rules allowed for cars over 1.6 L divided between two classes. Class A was for Sedans under 2 L., except for overhead cam engines which were limited to 1.6 L. Class B was for larger engines up to whatever IMSA decided appropriate for the Class which was the AMC Gremlin's 232 c.i. for the duration of the 'original' RS Series. As an aside, the "Baby Grand" moniker frequently applied to these IMSA Series was just that, a nickname. Around this same time a series that was officially designated Baby Grand (better and later known as the Goody's Dash Series) was sanctioned by NASCAR and consisted of 4-cylinder cars purpose-built to run NASCAR ovals. A few RS regulars are known to have run both Series with the same car making minimal changes to accommodate the difference in rules. Carson Baird, driving a Dodge Colt, was one of these 'crossover' competitors. IMSA RS The IMSA RS Series (for radial sedan) began as the Baby Grand Series, in 1971. Originally sponsored by B.F. Goodrich (therefore known as Goodrich Radial Challenge) until they dropped sponsorship midway through 1975 (or 1976) and then by Goodyear (becoming the