I have the Blue Driver. It's a little more expensive than some but works good and lots of features with live data.

Click the link for more info
https://www.bluedriver.com/

 

 

 

 

The issue is not the OBD2 reader, the reader to the phone is a digital data stream, it can't really be off. Your tires size could be throwing the speed off too, but you will NEVER get it that accurate. The problem is the GPS in the phone that it uses to calculate distance. Phones only have a 1Hz Max GPS. You need a device that has at least a 10 Hz GPS. I bought a VBox Sport, it has 20 Hz GPS that connects to an iPad or iPhone via BlueTooth. Drag Times did a review on the stand alone 10 Hz VBox and found it to be pretty accurate compared to actual strip times. One cool thing it does is tell you the starting test elevation and ending elevation so you can see if your going up hill or down. It does a whole bunch of graphs and stuff too, and will log speed and distance data, as well as brake testing XX to zero.


Sorry about using the same picture in a couple posts.





Mike