1976
The new 6 Series coupé, using the model code E24, was introduced to the press in March 1976, suggesting production commenced in 1975.
Initially there were two models available: 630 CS and 633 CSI. Karmann constructed the 6 series coupé, as well as the earlier BMW coupés. There were a total of 1665 units of the 630 CS (plus 410 630 CSi, bound for the United States) and 2858 units of the 633 CSi (this number also includes right-hand drive cars) produced in the first year, amongst a total of 4,933 cars produced for the year.[27]
1977
Production of E24 continued in 1977 at Karmann as a complete assembly until August, when only the steel body shell was made by Karmann and then shipped to BMW's plant in Dingolfing for assembly.[28]
Karmann-bodied cars are now rare and highly collectable,[29][30] particularly in original condition in early factory colours such as orange (028 Phönix), green (079 Mintgrün), and yellow (070 Golf) - the latter very rare.
1978
In July 1978, the more powerful 635CSi variant was introduced. The 635CSi featured a close-ratio 5-speed gearbox and a single piece black rear spoiler. The M90 engine was a single overhead cam version of the M1's M88 engine, its bigger bore and shorter stroke resulted in 160 kW and increased torque. The aerodynamic changes reduced uplift at high speeds by almost 15 percent over the other E24 models.[31]
1979
In 1979 the carburetted 630CS was replaced with the 628CSi;[32] this car had a fuel-injected 2.8L engine taken from the E12 528i. An anti-lock braking system became available as an option.
1980
In 1980, the fuel-injection systems changed from Bosch L-jetronic to Bosch Motronic.[33] The 635CSi central locking system could now be operated from the passenger door and trunk.
1982 facelift
In 1982 (1983 model year in the US), the E24 was updated with parts from E28 5 Series, resulting changes to exterior styling, engines, chassis, suspension, electronics and the interior. The struts in the new front suspension were double-linked ones, making the car less likely to dip under hard braking. The new rear axle was nearly identical to the trailing arm layout of the E28 528i, with a new pitman arm to control camber changes.[34] Meanwhile, the ventilated rear discs had proven a needless complication and were replaced with solid ones. The rust protection was improved considerably along with the facelift.[15]
The 635CSi engine was updated to the 3430 cc M30B34, which used a smaller bore and longer stroke than the previous 3453 cc M90 engine. The 635CSi became available with a wide-ratio 5-speed manual or a 4-speed automatic transmission.
1987
E24s produced after June 1987 were fitted with ellipsoid headlamps, as per the recently introduced E32 7 Series.[35] The front and rear bumpers and spoilers were redesigned to use a single design worldwide[36] (prior to this, models sold in North America used a different design from the rest of the world).
The 635CSi engine was updated to the higher compression M30B35,[37] which resulted in a power increase of 19 kW for engines with catalytic converters.