An Arduino Due CAN throttle monitor It requests the throttle angle of a Volvo S80 2008 and displays the response as a percentage on an LCD screen.
WARNING: This works on a Volvo S80 2008 model. You must first find out the correct frame to query the throttle angle and also the correct ID's. If you just test this with your car prior to adjusting the CAN speed and frame data, you might get into trouble. I take no responsibilty whatsoever if you damage your car. You must know what you are doing!
A library for the Due's CAN bus is available here: https://github.com/collin80/due_can
For a design of a dual CAN shield, check my blog http://s80ev.blogspot.ch/2013/05/springtime.html or http://arduino.cc/forum/index.php/topic,131096.30.html