Well, I have some news... But before I will answer what you said above...
I have the last version of JSGME, and your mod live togheter with a lot of other mods, tracks and cars, freeware and payware, including Thunderflash´s ones.
Everything running perfect at the exception of this one. (Indycar)
BUT ...
Last night I took the trouble to reinstall ALL the mods, including the tracks, the paid ones, the free ones, and the complete set of Thunderflash mods, all of them worked perfectly, but I did it just in case. I used the same and latest version of JSGME again. The ONLY change I made was to leave the Indycar mod to the bottom of the install list... And now the Indianapolis and Daytona tracks are working. Everything goes fine now. With exception of the Canapino´s car that does not make the texture change to that of the Argentine colors on the Indianapolis track or any other.
I'm not an expert on this, but I suspect that this automatic texture change system is part of the problem, as well as the coexistence with other mods. I hope this info is useful.