Science in Everday Life

I received a small auto compass as a gift yesterday. You know the kind: it attaches to your windshield with a small suction cup. The compass rose is printed on a small ball that rotates as you drive. The instructions for mine tell me:

"A compass uses magnets and is affected by metal objects, electrical wires, and magnets in any vehicle. Mount compass where it is not affected by these."

I just love it when a non-scientist writes stuff. Where exactly in my car is a compass not affected by metal, electrical wire, or magnets? Lots of metal in a car, lots of electrical wire in a car, and lots of magnets in a car (for as we all know from Maxwell's equations metal rotating in an electrical field induces a magnetic field.)

Maybe I'll just use this compass in my plastic car.
K-