Google didn't help (at least not in my time allotment). In case you didn't know it, a thief can insert a pry tool (popsicle stick?) and pry back the plunge pin that locks your gas tank flap, open the flap (yes, even with the car locked), and thereafter of course, simply open your gas tank. I recently came out in the AM to find my car locked, but the flap open...over 1/2 tank of gas stolen this way from my E46 M3. At $4/gallon for hi-test, look for it to happen to you next, if not to me again.

Nowhere have I been able to find a cap with the green insert shape that also has key lock feature. Does anyone know of a source? Thanks!