Now, there are a lot of ways to make it more descriptive, one of the best comparing by usefulness/complexity ratio is
"Cht" - for different "C"ar compared to the host
"chT" - for different "T"rack compared to the host
"cHt" - for anything else ("H"ack

With this system you can also have combinations like "ChT" - player has both different car and track to the host but everything else is the same