if (!strcmp("car", cmdtext[1], true, 3))
{
  if (cmdtext[4] != ' ') return SendClientMessage(playerid, 0xff0000ff, "Usage: /car engine or /car lights /car whatsoever");
  if (!strcmp("engine", cmdtext[5], true, 6))
  {
    // user typed /car engine
    // put functions here
  }
  else if (!strcmp("lights", cmdtext[5], true, 6))
  {
    // user typed /car lights
    // put functions here
  }
  else if (!strcmp("boot", cmdtext[5], true, 4))
  {
    // user typed /car boot
    // put functions here
  }
  else return SendClientMessage(playerid, 0xff0000ff, "Error: unknown /car command.");
  return 1;
}