Does anyone know what station in Munich has BMW M3's available for rent or how to go about finding out? Sixt's website has them listed in the fleet, but finding one is difficult. Perhaps none are available?

I am also planning on dropping it off in Frankfurt. Can these be rented one way?

On a related note, the BMW 3er lists GPS as a bookable option, but I've rented a BMW in Germany before where it was pre-installed in the dash. Of course, it was with Avis so I'm not really comparing apples to apples. Do the Sixt 3er's not come with it pre-installed?