Yep, during the post war period, German companies were prohibited from making airplanes, so Messerschmitt switched to making cars for quite a while.
No connection with BMW - Messerschmitt started building Aircraft again in the late 60's and later became part of the Daimler-Benz Aerospace conglomerate.
BMW had it's own microcar - the Isetta... Which had a proper reverse gear in it.
that's why subaru made their first civilian transport thingy too, it was a scooter i think called the rabbit. they used left over airplane wheels from when they made a version of the Mitsubishi zero during the war.