1988 BMW M6
6-cyl. 3453cc/256hp FI
With an experienced team and a lot of data.
The BMW 6-Series coupe had the rather unenviable task of following up on the Wilhelm Hofmeister-designed 2000CS, 2800CS and 3.0CS coupes, whose production ran from 1967-75 and was capped by the outrageous competition lightweight CSL “Batmobile.”
The new model range had to combine world-class performance with stunning elegance, and Paul Bracq was tasked with re-thinking BMW’s top-line car. The result was a squarer, more aggressive “shark-nosed” coupe, which would be built in various forms to 1989, culminating in the blisteringly fast M 635 CSi, which used the 24-valve M88 motor from the M1 and could hit 158 mph in European tune.
Bracq followed the design cues from the previous BMW coupe, with a divided kidney grille, large greenhouse and broad hood and trunk, but the 6-Series had thin B-pillars, and the bodies were assembled by BMW at Dingolfing instead of Karmann’s Osnabruck works.
Handling remained by all-round coil springs and McPherson strut front suspension, semi-trailing rear links, and recirculating ball steering. New to the 6-Series was speed-sensitive power steering, four-wheel disc brakes, and a complete warning light system to alert the driver about engine and electrical systems. The 2+2 seating saw a driver-angled dash flow down to a console that also separated the rear bucket seats.
The first 6-Series cars were launched in Europe as the 630CS, with the 3.0-liter six-cylinder engine, and a four-sped Getrag gearbox or three-speed ZF automatic transmission. The first U.S. cars of 1977 were badged 630CSi, with Bosch L-Jetronic injection after grumbles about the modest performance.
Engine sizes gradually increased to 3.2-liters then 3.5-liters, but the 6-Series really hit a bullseye with the M635CSi, which appeared at Frankfurt in 1983. Apart from the 282-bhp M1 engine, it had a limited-slip differential and the “track link” suspension from the big 7-Series sedans, which was designed to reduce oversteer. ABS brakes arrived at the same time, along with a five-speed manual gearbox or a four-speed ZF automatic.
Badged simply as the BMW M6, the 635CSi finally reach the U.S. in 1987, lavishly equipped with twin air-conditioners (and a beverage chiller in the rear), hand-stitched Nappa leather interior with eight-way power front seats, and an eight-speaker sound system. Distinctive M6 details included M badges front and rear, a larger front air dam and rear spoiler, matching color side mirrors and BBS wheels. The cars were fitted with new ellipsoid headlights, which directed a more precise beam onto the road.
The M6 could manage 0-60 mph in 6.1 seconds, a quarter mile in 14.7 seconds and cruised easily at 140 mph. It retailed for $55,950 but if you wanted the same look with more modest performance, the identical appearing L6 model was $6,000 less, though only available with an automatic transmission.
BMW electronically limited even its sportiest models to 155 mph in the U.S., but Rug Cunninham BMW ran a de-limited M6 in the 1989 La Carrera Pan American race in Mexico and reported a top speed of 176 mph. In all 5,859 M 635 CSi cars were built between 1983 and 1989, with 1,787 of those being the slightly detuned U.S. model BMW M6.