1985 635CSi

Robert Bosch for President
The 1985 model year marks the end of Bosch's teeth-cutting stage and the beginning of Motronic engine management control as we know it today. Motronic version 1.0 adaptive offered variable operating parameters according to sensor inputs and provided the basis for the future of performance tuning--the eprom upgrade. But this didn't happen overnight. Not until the early 1990s did companies and luminaries such as AutoThority and Jim Conforti totally unravel BMW's code and rewrite it for more performance-oriented use. Meanwhile, though, BMW finally had the beginnings of a power increase it so desperately needed in the U.S.

Engine displacement was finally increased to rest-of-the-world spec at 3430cc (3.5L), and the U.S. E24 finally became the 635CSi. Power was now up to 182 bhp at 5400 rpm and 214 lb-ft of torque at 4000 rpm, the latter eclipsing the European-spec 633CSi. However, the U.S. engine was still hampered by a low, 8.0:1 compression ratio and exhaust restrictions, meaning it was still grossly underpowered by European standards, where the 10:1 compression, non-catalyst 635CSi cranked out 218 bhp at 5200 rpm and 228 lb-ft of torque at 4000 rpm. The low compression ratio was mandated by low-octane gasoline and the inability of early Motronics to deal with the combination of high compression and exhaust restriction in the absence of knock sensors. Later, in the 1990s, the 1985-on U.S.-spec 635CSi would respond dramatically to a simple ECU chip upgrade from either of the aforementioned suppliers. Today, a Conforti chip remains the single best engine power upgrade for the U.S.-spec 635CSi.

The Getrag five-speed overdrive manual gearbox remained unchanged for the rest of E24 production, and the 3.45 differential remained for manual gearbox cars, with limited-slip optional. The optional new ZF 4HP22EH automatic transmission marked the initial mating of electronics with the slushbox, with long-term durability results that are now matters of history. In theory, though, the 4HP22EH was interesting in that it provided an overdriven fourth gear combined with three electronic programs--normal or "E" mode, sport "S" mode which locked out fourth gear overdrive and held each gear to the redline under full acceleration, and "1, 2, 3" mode, which provided manually operated individual gear hold. In practice, most drivers likely played with "S" and "1,2,3" a time or two and then simply left the thing in "E."

The addition of anti-lock brakes (ABS) marked the proverbial foot-in-the-door for today's plethora of electronic nannies, albeit at a far more useful level. Inside, power leather seats featured three-position memory that was very useful for cars used by multiple drivers. Cruise control was now standard with both manual and automatic, and a new steering wheel greeted the driver as did a new audio system. The multiple-function onboard computer (OBC) made its way into BMW life, bringing useful information to the big coupe driver. Average mpg, average speed, outside air temperature and miles remaining until tank empty were among the more useful functions, along with a vehicle disabling code function. However, without the owner's manual you won't get far with the OBC.

Outside, the 1985-on 635CSi sports perhaps the best front airdam BMW ever designed. Constructed of durable but flexible ABS plastic, this part completely shrouds the lower front valence panel, creating downforce on the front suspension while housing effective large foglights and incorporating a cover for the front tow hook. Most unfortunately, this part is no longer available from BMW. We hope BMW Mobile Tradition will step up to the plate and reproduce this and other BMW aerodynamic parts for older models. Two different factory rear spoilers were optional accessories, and both were functional in providing downforce on the rear suspension.

A curious L6 model emerged in 1987, with more leather inside than a Berlin spank slut has outside. The dashboard and headliner were even covered in leather. The car's cockpit smelled like a tannery. It was classic U.S. market overkill. Still, like the lady, it was not uninteresting. Unfortunately, the L6's leather dashboard quickly deteriorated under North American sunshine in the absence of regular and copious high-end leather care product application, and no manual gearbox was available. A matching L7 headed up the E23 7 Series in the same model year. There was no snootier statement at the country club than his and hers L6/L7 arrivals. Enthusiasts gagged.