I also believe Test Track and Radiator Springs Racers are too similar. The problem for me lies in the vehicles themselves (both themed as cars) and the slow dark-ride portion followed by the high speed ending portion.I get what you’re saying but it’s also like saying we shouldn’t have Haunted Mansion and the Little Mermaid ride in MK along with Nemo and Epcot because it’s the same ride system
Journey to the Center of the Earth at Tokyo would be a better differentiator, IMO (though unlikely due to the IP mandate). The ride vehicles themselves aren't supposed to be automobiles.