Selection criteria for microcontroller to read data from a car's CAN bus (from OBD2 to microcontroller)
If you choose a microcontroller with an integrated can controller then you need to buy only the CAN transceiver. If you want to use Arduino, then a CAN controller and a CAN transceiver or a single module with both CAN transceiver and CAN controller built in can be used.  

Microcontroller decision is left to you depending on other product requirements such as memory, interfaces, performance and power.

Please take care of ESD, filtering and transient protection too.

Random example of a CAN controller