Because it is illegal to run out of gas on the Autobahn, drivers who find themselves in this predicament can be subject to fines. The Autobahn, Germany's legendary federal highway system, is known for its liberal approach to speed limits. This may explain why it is also illegal to walk on the Autobahn.
The ban on both running out of gas and running on this German highway system means that those who find themselves running on empty may have to walk to the nearest gas station. This self-saving measure may also result in fines, likely because of the hazard that is posed by stopped cars and people on a roadway where people might be allowed to drive as fast as they possibly can.