Vintage R&T Review: Opel Diplomat V8 – “Something That GM Could, And Should, Build In The US”

Now that’s an interesting line, as this Diplomat was actually seriously considered as the basis of the 1976 Cadillac Seville. As the story goes, the big Opel’s body tolerances were too tight for GM to build in NA, although I suspect that may well not be the full story. But the even more interesting line in this short review is the last one:

“Why doesn’t GM import the Diplomat? Simple. It would meet head-on with upper Olds, Buick and Pontiac models and could no more achieve the prestige of a small Mercedes than it does in Europe. But if they gave the Chevy Nova sedan its brakes and rear suspension, hmmm…”

This was in February of 1972, well before GM had committed to build the Seville using the Nova as its basis. And no, they didn’t give it the Diplomat’s DeDion rear suspension and brakes.  And although it tried to take Mercedes head on, it never made the slightest dent in Mercedes continued growth in the US.

Now if they had done that ten years earlier, it might have been a different story.


The big Opels were something of an oddity in Europe, as they had always been something of a 7/8th scale GM sedan. The Kapitän and Admiral date back to the 1930’s, and were quite popular in the ’50s, as a local cheaper alternative to a then-still desirable big GM car from the US, as well as a Mercedes. But that all changed rather quickly during the ’60s, when big American cars lost their prestige value, and Mercedes, BMW and then Audi became the status symbols of an ascendant domestic industry. The big Opel’s image drooped.

So for the new generation that arrived in 1969, Opel tried to make it more “European”, with improved chassis dynamics and a new De Dion rear suspension. But in styling it still leaned more to the US than what was being done in Europe then. Handsome, but decidedly American with a Euro touch. The same mostly applied to the interior: well done, quality materials, full instrumentation, but with an American vibe.

The top of the line, the Diplomat came with a Chevy 327 (5.4 L) V8, rated at 230 net DIN PS/227 net hp. It was essentially a 275 (gross) hp 327 Chevy teamed up with the ten THM-350 automatic. That was its trump card, as V8s were still an extreme rarity in Europe; Mercedes’ 3.5 V8 would just be arriving that same year, but at a considerably higher price point. The Diplomat offered a relaxed, torque-rich automatic drive train that was something still quite out of the ordinary, never mind that it utterly ordinary in the US.

This generation of the K-A-D Big Opels was decidedly not a success, and they were not replaced, although the Rekord-based Senator did cover the lower end of their range. Europeans were done with American cars, real or German-built.

But it was clearly a better Chevy, or any other American GM car at the time, in terms of its dynamic capabilities as an all-round sedan. And as such, it would have been interesting had GM chosen to build it in the US, as a better Seville or?