I've never understood why GT7 forces cars to slow down on–track instead of the sane and easy thing to do: adding the penalty time onto the total race timer, and/or allowing the penalties to be served during pit stops.
The sheer speed difference in speeds after a car serves its penalty and the cars that haven't is just a hazard. Not to mention how there's no real world precedent and therefore commonly accepted etiquette for serving these on–track penalties; should you move off the racing line to allow cars to pass, at the risk of appearing to defend the coming corner? Or stick to your line and leave it to the passing cars pass safely? The fact that cars serving the forced slowdown penalty is ghosted implies that passing cars are supposed to drive through the slow car, but the ghosting system doesn't give a warning as to when it will un–ghost a car. It's a system that just seems to invite trouble for no apparent reason.
If the penalty system didn't force slowdowns on–track, drivers would have no reason to go touch grass. In a competitive setting, players are supposed to find and go for every last advantage, so this issue is entirely self–inflicted by PD. A part of me respects the creativity of the drivers who found this exploit to begin with
Plus, drivers minimising their speed loss by dipping two wheels off the paved surface seems completely trivial in comparison to the issues I described above.