stock IsPlayerInCar(playerid) {
	new count_cars;
	for(new i = 0; i <= sizeof(cars_array); i++){
		if(cars_array[i] == GetVehicleModel(GetPlayerVehicleID(playerid))){
			count_cars++;
		}
	}
	if(count_cars > 0) {
	    return 1;
	}
	return 0;
}

public OnPlayerStateChange(playerid, newstate, oldstate)
{
	if(newstate == 1) {
	    TextDrawDestroy(showspeed[playerid]);
	}
	if(newstate == 2) {
	    if(IsPlayerInBoat(playerid)) {
	        SendClientMessage(playerid,COLOR_YELLOW,"Type /fish to go fishing.");
	        SendClientMessage(playerid,COLOR_YELLOW,"Type /lock to lock the boat doors");
	        SendClientMessage(playerid,COLOR_YELLOW,"Type /unlock to unlock the boat doors");
		}
		if(IsPlayerInCar(playerid)) {
		    SendClientMessage(playerid,COLOR_YELLOW,"Type /lock to lock the car doors");
		    SendClientMessage(playerid,COLOR_YELLOW,"Type /unlock to unlock the car doors");
		}
	}
	return 1;
}


Array is from http://michaelnets.com/sa-mp/vehicles.php