Arduino and Can Bus shield

Hello all,
I am working on a small project on my car and was wondering if anyone had experience using an Arduino/CAN BUS shield combination to connect sensors to the already existing CAN? I have the arduino working fine with a temperature sensor, linear actuator, and lcd, but was wondering if it was possible to use the cars already existing temperature sensor? Could I use the car battery as the main power source for the sensors I wish to include? Which, if any, shield would you recommend pairing with the arduino?
Thanks in advance for any help or suggestions!