Reading CAN data with Canshield and Arduino

Hello,

I'm looking for a little expert advice.
I drive an Audi, manufactured in 2008, which has an aftermarket exhaust flap. So far, I can only operate it using a manual button.
I want to make the circuit dependent on the vehicle's speed and other parameters. The circuit itself is already working, but I'm not able to retrieve the vehicle parameters from the CAN bus. I have a Canshield from Sparkfun and an Arduino Uno.
Has anyone by chance successfully read data like speed and RPM from it before?

Best regards,
Daniel.

Can you generally receive data from the CAN bus, but you don't know which specific data points represent the speed and RPM?

Normally, you need the vehicle's communication matrix to know where specific information is located. However, engine speed and vehicle speed can also be retrieved as diagnostic data.