Well, first and foremost, use the big metallic shield that the manufacturer provided you when they built the car - ground your hood. Run a couple of heavy braided cables from the rear corners of the hood to the body, making sure to scrape away the paint where you securely bolt the braid to the hood and body. Make sure your controller and any metal enclosures for other EV drive components are securely grounded to the car's body/chassis
Toroidal cores made of ferrite can be used to suppress noise traveling on wiring. These come in a variety of sizes, and can be quite effective at isolating noise at the source. They can be added to low current wiring as well as high current conductors.
Bypassing DC wiring with electrolytic and ceramic capacitors is useful, but probably not effective for high current conductors in the traction motor supply circuits.
Much of your efforts should go into determining if the noise is entering the radio via the car's DC supply wiring, or is being radiated and picked up by the radio as electromagnetic interference. Run the radio on a separate battery as a test to see if it's being fed noise from the car's electrical system. Try running a battery-operated portable radio inside and outside the car and see if it is affected.
Make sure you have an effective antenna, and that the cable from it is properly shielded and grounded. Try isolating the entire radio and antenna from the car's ground system, especially if a portable radio is unaffected by running the motor and controller.
If all else fails, get to like FM radio programming. It's a better system all around in most respects.
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