VirtualWire send multiple variables at once

It would be more efficent to send the data in binary form:

  const char * timestamp = "2012.10.13";
  float voltage = 4.59;
  float current = 0.36;
  float power = 1.65;

  int size_of_float = sizeof(float);
  int size_of_timestamp = strlen(timestamp);

  uint8_t buffer[size_of_timestamp+size_of_float*3];
  void *p = buffer;
  memcpy(p, (void *)timestamp, size_of_timestamp);
  p += size_of_timestamp;
  memcpy(p, (void *)&voltage, size_of_float);
  p += size_of_float;
  memcpy(p, (void *)&current, size_of_float);
  p += size_of_float;
  memcpy(p, (void *)&power, size_of_float);

  vw_send(buffer, sizeof(buffer));

And you could also send the timestamp as a 32bit integer instead of a string.