Send command for RC Car

Ok thanks for the explanation,

I add like you say this line:
char ltr = inData[0];
inData[0] = '0';
int val = atoi(inData);
Serial.println(val);

after // The end of packet marker arrived. Process the packet

end send in serial monitor of other arduino this line: "<Arduino!>"

But i don´t receive anything in serial port of my receiver.