In other words, was it perfectly normal for West Germans to enter DDR territory by car, train, etc? I guess I am in need of a little run-down of what life was like for both West and East Germans living outside of Berlin at the time of the wall.
West Germans could drive to West Berlin on certain East German highways which were designated as transit corridors by mutual agreement. Eastern border guards searched Western vehicles at both ends of the trip, to ensure they didn't spend an unusually long time in the country - a possible sign they could have picked up East Germans who wanted out. (A few Easterners did manage to escape with Westerners who modified their cars to hide them.)
West Germans were not allowed to deviate from the highway, and could only stop at gas stations/restaurants set up specifically for Westerners - a reliable source of hard currency for the regime. But Eastern and Western vehicles did share the same motorway. I've often wondered what Trabant-driving East Germans must have thought as they were passed by West German Fords and VWs (not to mention BMWs and Mercedes-Benzes).
Commercial trucks had their cargo bays and trailers sealed upon entry to the East, to make sure no one could sneak on board.