You made awful little cars like this Kadett
But you also made fabulous cars like the Opel GT, an startling French-German car that made the Corvette look silly.
By the mid-1970's Opel had produced the Manta, a terrific sports coupe, which really showed up its Buick master.
Opel ceased to be imported but it always remained an important element of GM's European operations. It also provided components and innovation to GM's corporate efforts to produce better handling, more compact sized sports sedans. When GM faced bankruptcy in recent years divesting itself of Opel was considered an option but GM found another way to retain its investment. Today Opel actually owns Vauxhall, GM's British stepchild, and has close tie in with Peugeot (PSA) of France.
As part of GM Opel must have the "right" to piggyback onto the Monza nameplate, last used in a rather awful Vega offshoot in the '80's, but used to perfection [if to the annoyance of F1 fans] in the Corvair.
So there's a new Monza, a concept car, introduced by Opel this week at the Frankfurt Auto Show.