Maximum sampling rate of Arduino adapter to OBD2

What is the Maximum sampling rate of Arduino adapter to OBD2 ?

The ELM327 says it can return with the answer after less than 10 mls. I measured the time to be 5.5 to 8.2 milliseconds.

When I try to sample the OBD2 via Arduino every 20 mls (for sure after answer has arrived) the Arduino stalls. I sample it every 21 mls. and it works.

1/12/2015 I found an explanation searching Freematics.com forum : 0BD-II polling frequency depends on different cars. On a VW Scirocco or Mitsubish Outlander, the frequency is about 50Hz. - which is like every 20 mls