I have been shoppping around to find a bank to get the best car loan I can, but they all keep telling me about their comparison rates and I still don't understand what this is and what it means to me! Can anybody clarify this for me and explain exactly what it is?

Thank you!

You didn't tell me your country of residence. Different countries use a different method of calculating the interest to be repaid.

If you are in the USA, then you may try to compare different rates at this site:
Auto Loan and Car Finance Calculator

If you are from Malaysia, then you may try this site:
Malaysia Car Loan Calculator Meshio.com- a Malaysia Personal Finance Blog

LYC, Malaysia.