Newbie Dr.Prius Question

Hi All,

Planning to buy the $12.99 for 3 cars on Dr. Prius - just to see how much life my hybrid battery have. A few questions:

1. How does the app know which three cars I am going to use it for...does it track/record the VIN through the OBDII port onto the app?

2. Is it truly unlimited testing for those 3 vehicles?

3. Does it work with non Prius...like other Toyota hybrids?

4. Lastly, if I were to delete the app and re-install it a year later, how will the app remember my vehicle as one of the 3 vehicle on the $12.99 plan?

Thanks!