[Riwerry]

Well, when you want to change string, why are you using strmid? I'd suggest you to use strcpy function. (fastest method for copying strings)

pawn Код:

//To the top of your script
#define strcpy(%0,%1) strcat((%0[0] = '\0', %0), %1)
//Usage: strcpy(dest[], source[], sizeof (dest));

//Then in your code
strcpy(MyVehicle[vehicleid][MyVehOwner], NameOfPlayerToSellCar, sizeof (MyVehicle[]));

NameOfPlayerToSellCar change it for variable of player name that are you going to sell car to.