The buttons under the radio? Commentor IXXI was very nice and shared the following info
The Buttons under the Radio is a Shortwave Band Spreader. The Numbers represent the "Band" in MHz or "Meter". The Band Spreader worked as preselector mostly the User also bought an extra long Antenna (1,25m) with Crank drive height adjustment (Bosch, Kathrein, Hirschmann) for optimal fine tuning.
Most Shortwave Spreaders allowed to store one station for each Band. Most sought after Spreaders are the Becker Auto Super units with clockwork driven automatic search and storage. http://en.wikipedia.org/wiki/Shortwave_radio#Frequency_allocations
The "longer" bands where also called "marine bands" as they can pic up signals fom all around the world depending on the weather so even in the US you coud listen to european SW Stations like BBC, RIAS, ERF, RTL, AFN oder Deutschlandfunk. On the other hand mostly not while driving... Still today you can buy new SW Radios with Band Spreader
the paper in the window that describes the car descibe the car as having an optional Marine Band radio, is that what the numbered buttons are? Seems most likely