Hmmm, are you sure, that htey were original German plates and not only one US-made fake on the front on a car, coming from an US-state, where a front plate is not required? It's very unlikely, that it's an original German car, because the Ford Freestyle never existed here.

Otherwise: maybe it was a car from a Bundeswehr-soldier, stationated on the Luftwaffe-base in Alamogordo/NM. But I'm not sure about the plates for their private cars. The military plates are unique, made as the regular http://kennzeichen.pj-web.de/kenzdeu/img/bundeswehr.jpg but with only four ciphers.