My theory on this, during testing of the Tomahawk X it achieved Ludicrous Speed, went plaid, and very nearly ripped the fabric of GT space-time. Luckily the active aero was able to slow things down and bring it back from the brink, just. After that experience they had to do something. And that was to remember Route X has was not supposed to be on the Moon in the first place. Silly programmers...
Ok, it was a little out there I admit. But, that was how I figured a stock C7 could top 230mph. They goofed up and used their moon air resistance values I assumed. I figured PD gave the moon a low air resistance value, not zero though, it is a game after all. Every other track recieved the correct value possibly.
Hey, its just a theory.