#define MAX_CARR 4
new carnameidd[MAX_CARR] = {
	1,
	2,
	3,
	4
};
-------------------------------
public OnPlayerEnterVehicle(playerid, ????, 0) {
	GameTextForPlayer(playerid, "You entered this vehicle, TEST", 5000, 3);
	return 1;
}

De ???? moet dus zijn in van de carnameidd.