When you deliver your vehicle to your mechanic, he connects an external piece of equipment that reads the current health of your car. The AutoPi is able to do the exact same thing and warn you about possible faults.
You can even reset fault codes from your car, thus potentially saving a trip to the mechanic. All the information can be extracted through the OBD port in your vehicle.
How to do it?
Benefits of readout/reset fault codes
If you reset fault codes on the vehicle yourself, you will at least save a trip to the mechanic. In addition, you will most likely save $250-800 easily as mechanics in many cases tend to charge a lot for the small configurations + the service itself.
It also give you lots of useful information about your vehicle and you might be able to notice or even fix some issues in the future yourself.
You will also feel like a mechanic yourself when you fix something you had to run to a mechanic before.