Was it a small jetliner, with an odd configuration of engines mounted on top of the wing?
If so, it was a VFW-614, an early regional jet that was a joint project between the German and Dutch aerospace industries.
They entered service in the mid 1970's, but few were built. It was hopelessly uneconomic to operate and expensive to buy and maintain.
The engines were the Anglo-Frence M45, a version of an original engine designed for the late 1960's AVFG, (Anglo French Variable Geometry), a combat aircraft rather similar to the later Tornado. The AVFG was cancelled at an early design stage in 1967.
The Luftwaffe brought 3 VFW-614s, and used them until a few years ago.
Alternatively, if it was a large executive jet with 4 rear-mounted engines, maybe one of the Lockheed Jetstars that I believe were operated by the Luftwaffe at that time.
This is off the top of my head, is there a picture of this aircraft in the photo section?