I've been having this too, I'n pretty sure it was just my internet not being able to properly connect to those drivers. Makes every race pretty boring.
Quick race is always like this for myself and many others .
Open lobby still has the invisible cars issue also .
You can fix the open lobby issue temporarily by having a "Fixed Host " . However it doesn't / didn't last long as the more people that leave and join , the more pronounced the invisible car effect becomes .
Don't know if todays maintenance fixed the issue , but I highly doubt it . PD servers for GT6 have always been sub standard .
