From the archives: In an age of multiple models and badge bewilderment, BMW offers a standard enthusiasts can cling to no matter where the winds of change may blow.
When a BMW model wears the “M” emblem, it means something very special is going on beneath the skin—particularly that portion of the skin stretching between the front bumper and the windshield.
In the case of the M6, that something special includes six cylinders, two overhead camshafts, 24 valves, port fuel injection with Bosch Motronic engine management and 256 bhp. That’s enough to make BMW’s graceful 6-series coupe into one of the most seductive high-roller hot rods available anywhere.
This story originally appeared in the 1988 Sports & GT Cars Issue of Road & Track.
This engine differs considerably from the sohc six that has powered U.S. versions of the 6-series since its 1976 introduction. Besides the extra camshaft and 12 more valves, it has a substantially higher compression ratio (9.8:1 versus 8.0), machined intake and exhaust ports and individual throttles feeding each cylinder. Total displacement is only 23 cc greater than the 2-valve engine because the cylinder bore is 1.4 mm bigger and the stroke only 2.0 mm shorter.
If these specifications are the sort that you’d associate with a racing engine, your association is accurate. The M6’s Type S38 powerplant is a direct descendant of the BMW M1 powerplant that blazed onto the scene a decade ago. Though the BMW super-coupe never really covered itself with glory on the racing circuits—it very quickly became a car without a class—it became a rolling testament to where BMW intended to go with future powertrains and how racing was likely to figure in future development.
And this is why the M badge has come to symbolize an important trust between BMW and the driver, particularly the driver who has little interest in compromises. The M is badge shorthand for BMW Motorsports GmbH, BMW’s semi-autonomous competition subsidiary, and any car wearing that badge has been developed to BMW Motorsports specifications. Although there are those who label the various M entries as homologation specials, cars built only in sufficient quantity to justify their inclusion in various production-based racing classes, we are inclined to believe that BMW’s management perceives these race-based street cars as the expression of what the company is all about.
Viewed in the context of an automotive environment that still includes high-torque American V-8s and big-boost turbo motors, the S38 engine is deceptively subtle. Its power characteristics are electric-motor linear and, typical of 4-valve engines, there’s not much punch at the bottom end of the range. It takes 4500 rpm to achieve peak torque, and progress toward this goal may seem to be rather deliberate. However, a look at the test computer readout belies these impressions. Although the engine has 3570 lb of car to propel, 60 mph comes up in the 7-second range and top-speed capability is in the rarefied region of 150 mph.
Provoked into this kind of haste, the twin cam six emits a gratifying snarl, compounded of two parts induction noise and one part exhaust note. But at everyday operating rates the S38 is library quiet, and regardless of pace it’s as smooth as ancient cognac.
True to the M code, the accouterments accompanying BMW’s super six are also race worthy. The front brakes employ extra large rotors with 11.8-in. diameter vs 11.2 for the more sedate L6 edition of the coupe. ABS is standard, of course, as it is with all BMWs, and there are Bilstein gas-pressurized shocks at all four corners of the independent suspension system, with twin-tube versions at the front. Ride height is 0.4 in. lower than the L6, rear springs are progressive rate, the variable-assist power steering has been calibrated to improve on the already commendable road feel of the L6, and the wheel-tire package is a bit more aggressive—240/45VR-415 vs 220/55VR-390.
There’s also only one transmission option—a heavy-duty Getrag 5-speed that sends power to the rear wheels via a limited-slip differential.
What this impressive inventory adds up to is a car that knows how to put the S38’s power to good use. Although the M6’s maximum adhesion might be improved considerably by substituting a set of Goodyear Gator-backs for the metric Michelins, the big coupe nevertheless displays a delightful level of athletic agility. With its substantial weight snubbed down by the aggressive suspension tuning, the M6 changes direction like a border collie and absolutely thrives on high-speed sweepers. A combined development heritage of race tracks and Autobahnen gives the M6 super-high-speed stability, and braking performance is equal to the car’s other capabilities.
Handling of this caliber almost invariably extracts some sort of penalty in the area of ride quality, and the M6 is no exception to this rule. While lovers of level cornering and crisp steering response will make this trade without hesitation, not everyone will love the M6’s level of firmness—which is why there’s also an L6.
However, even though the M6 can be a trifle harsh on bumpy roads, this is not to say that it’s hopelessly stiff. This is, after all, a luxury car—just check the price tag—a classification that one glance inside should confirm. Although the 10-way power adjustable seats feature the pronounced bolstering that embellishes control when the scenery starts appearing at a lot of odd angles, that’s real leather stitched (by hand) onto the various surfaces and there’s more of it on the door panels, steering wheel, dashboard and console. That’s also velour carpeting underfoot and a two-way electric sunroof overhead.
Like most BMW offerings these days, there’s plenty in the way of onboard electronics—a trip computer as well as a 7-function monitor system. Virtually every comfort and convenience feature is power-operated, which helps explain all that curb weight—electric motors are heavy. And to make long-haul cruising even more pleasant, there’s the inevitable premium AM/FM cassette sound system, in this case with anti-theft provisions and hooked up to an array of eight speakers.
If there’s any criticism to be made inside the car, it’s that fore and aft seat travel could be lengthened; long-legged drivers may find themselves a trifle confined. And even though the steering wheel has a telescoping column, the absence of a rake adjustment means that some drivers may find themselves forced to adjust to the car rather than vice versa.
On the other hand, these are adjustments most of us would be only too happy to make, given the opportunity. We’ll take the red one.
Keyword: The BMW M6 Is Proof That Racing Improves the Breed