i'm not sure if anyone has brought this up to the mythbusters yet, but there is another way to jam the police radar gun. you were on a close track with using the microwaves on the front of the car, but it didnt quite cut it. police radars run on the K band at 22 ghz, or on the X band at 10.525 ghz.

most microwave intruder alarms and motion detectors (mounted over automatic doors in supermarkets & banks, etc.) contain a Gunn type transmitter/receiver combination that transmits about 10 kilowatts at 10.525 ghz. These units work perfectly as jammers.

Just a suggestion if you should decide to revisit this myth

P.S. does not block radar from the side or from behind. only the way the jammer is facing