It seems most of GTP has been left in the dark on this matter as it's a no-no to discuss on here apparently? Anyway EVERY single parameter of the car has been discovered now,you have no clue how deep it has infiltrated online racing, yes the 50,000HP Fiats are easy to spot, but see if you can spot my Super GT car with extra downforce, 8 speed trans, X2010 suspension and grip multiplier on the tires...the one that still meets 1100kg/493HP Super GT regulations. Over the last week or two the documenting and sharing of values in the save data has multiplied tenfold, allowing for the useless SSRX cars and also cars that look entirely stock but have a huge advantage over the equivalent of someone who doesn't know how to hack. The reason it hasn't been fixed yet is because the parameters being swapped/multiplied are the same ones that are modified in EVERYONE's game save, if you have a car that has any tuning part on it you could also be confused with a hacker, hence why it's virtually impossible to stop.
and to the guy talking about reporting every hybrid he sees online, just a word of advice, don't waste your time, reporting someone on PSN does ABSOLUTELY NOTHING, trust me.