E24 6 Series
Photography by Courtesy of BMW AG
With more engine variations than any other BMW coupe, there is a 6 Series for almost anyone inclined to own one. That there are so many so inclined is reflected by value retention unequalled by any other mass-produced BMW except the coupes preceding it (the E9 "CS").
We'll stick to U.S.-spec cars, except for a discussion of the European-spec 635CSi and M635CSi, because many have found their way here through private importation.
Birth of the E24 6 Series
In designing the E24 6 Series to suit multiple markets, then chief pen-and-clay man Paul Bracq, who created the BMW Turbo in 1972, confronted the reality that BMW doesn't always mean the same thing in Germany as it does here. It was a time to revel in traditional BMW styling, performance and personality, even though the influence of the 1972 Turbo is clearly evident on the E24 exterior. As it is even today, the German concept of sporting luxury does not always translate into American notions of, well, luxury luxury. And in many other countries, it is not a stretch to say BMW is better known for motorcycles and police cars than luxury automobiles. Still, no one here complained about the look of the new car; it was the "go quotient" that garnered criticism, and for the same reason as the E24's stablemates--more weight and less power. It seemed, at least in the U.S., that BMW was reverting back to the pre-E9 era in terms of power-to-weight ratio.
In fairness, the E24 had to weigh in heavier than the E9 due to added crashworthiness. BMW really got serious about the front and rear crumple zone, reinforced roof panel, a bar extending the width of the cockpit behind the dashboard and reinforced rear bulkhead behind the back seat. U.S. models, of course, carried on with the big aluminum "crash bumpers," which would mar our 6 Series until 1988 when BMW debuted world bumpers. In 1977, first year of the U.S. E24, that added up to 350 lb more than the last 3.0 CSi.
Now, it's a fact of life that everything gets bigger and heavier in time--cars as well as people. We are willing to put up with added girth in return for function. But what happened to U.S.-spec E24 engines was just a sin. American emissions laws mandated use of a positively horrible exhaust gas recirculation (EGR) system incorporating an air-injection system component that was akin to bolting a two-by-four board across the cylinder head exhaust ports. High-compression pistons were out of the question, and, in fact, low compression was the order of the day due not only to the EGR system but also to the demise of serious high-octane gasoline--this was way before the knock-sensing ignition emerged to save the day for compression ratios. The result was that horsepower and torque nosedived. Due to the thermal reactor exhaust manifolds, cylinder-head warpage problems in the E24's M30 engine appeared almost instantly in the heat of American summers.
You'll get varying opinions on this, but for me there were five distinct E24 generations in the U.S. market: 1977, 1978-79, 1980-84, 1985-87, and 1988-89. The prime factor here is engine configuration of the non-M models.