Road test: BMW 750iL
Doyen of the dozen?
When Eberhard von Kuenheim, Chairman of the Board of BMW AG, described the new 750i as “an aspirant for the leading position in the international automobile hierarchy”, he was only stating the obvious. Munich’s priciest product, at £53,750, is one of the very best cars currently available. Silken in character, startling in performance, sybaritic in furnishing, it can waft in a tall overdrive top to a City board-meeting, or snap down into the autobox’s Sport mode and thread itself along demanding B-roads like a sportscar. And all of this in near-silence and with a poise which remains untroubled by poor weather or poor roads.
As the 735i has already been described in these pages, it is worth concentrating here on those elements of the 750i which differ from it. This is one of only four V12 car engines in production; the others, Jaguar, Ferrari and Lamborghini, all owe their origin to an earlier day, a less sophisticated era of carburettors and vacuum advance mechanisms. Now, with the first German production V12 since 1939, we see a new age of faith in electronics, to the extent that BMW has dispensed with any mechanical connection between throttle pedal and engine. Instead the driver’s foot operates a potentiometer whose signals are obeyed by individual motors on the throttle butterflies. That is one example, but in every area the car’s sophistication is comprehensive.
A V12 engine is not, of course, just about power, or even torque, although the Munich unit churns out a full 90% of its huge 325 lb ft as low as 2500 rpm, and an impressive 78% even when virtually idling at 1000 rpm. More important is the smoothness of twelve cylinders and the silence of expensive engineering.
Waiting at the lights the BMW’s idle simply cannot be felt or heard; depress the heavy throttle and only a shiver betrays the acceleration. Under load, though, more of a rumble can be heard than from the Coventry unit, but the overall silence is almost uninterrupted. At 30, 70, or 120 mph the radio volume needs no adjustment, the passengers suspended in a cocoon of calm. It is just as well that there is a pre-settable speed limit alarm.
Coventry is of course, currently running on handicap in that its own magnificent V12 engine, now seventeen years old, has yet to be installed in its superlative XJ40; when that combination is available, it will be Munich’s biggest threat, not least because of Jaguar’s extraordinarily competitive pricing. The Jaguar’s ride is the softer, though anything but slack; it has a fluid and progressive response both to road inputs and to steering movements which arguably gives it an edge in the luxury field over the sharper BMW; but then that very sharpness is seen by some as desirable.
Motor Sport has commented already about the sumptuous furnishings of the 7-series cars; in 750iL shape everything is standard from remote locking and window-closing, electrically-adjustable seats front and back, full leather upholstery, and all-round heated leather seats, down to heated door-locks and air-conditioning which can be pre-set to cool the car before getting in. Even the rear headrests only pop up when a seat is occupied.
And if you feel that this much luxury is sinful, brace yourself for the proposed super-luxury package the company is working on. It seems that for a rare few, the cost is simply not relevant.
Bodily, this year’s 200 or so British V12 owners can display their good fortune by the wider BMW grille and matching bonnet, and twin square exhausts, a styling which which also appears on the BMW K100 motorcycle. The most significant change, however, is almost invisible: all V12s for Britain will be the longer-wheelbase L model which puts no less than 41/2in extra legroom behind the front seats, with correspondingly wider doors. So subtly is this done that it only really shows when the two models are side-by-side, unless you are seated within, lounging back on the heated leather with room to cross your legs.
Whether in V12 or straight-six form, the big BMW is beautifully crafted in every conceivable area. Pull one of the heavy stalks and the screen is rinsed by four perfect crossbow-accurate jets, then cleaned by heavy wipers which adjust their pressure according to road-speed. Separate temperatures for driver and passenger are manipulated by silky-smooth thumb-wheels, and yet more controls allow rear passengers to choose their climate too.
All British spec cars are fitted with the Electronic Damper Control system. A rocker switch on the console flicks between “sport” and “comfort” and the device is tied to the automatic self levelling rear suspension so that even with soft damping and a full boot the car remains horizontal. But it can be psychologically risky to give the driver the choice; he is likely to start to worry about whether he is in the correct setting for the circumstances and wondering why there is no central position.
In BMW’s case there is a clear division between the characteristics in the two modes: “sport” means sharp and precise at motorway speeds but distinctly abrupt over 30-50 mph bumps; “comfort” makes the ride exceptionally smooth and controlled over the longer undulations but detracts from stability at high speed, the fine precision of BMW’s Servotronic steering being dissipated in extra body movement. And it is still edgy over holes and ramps even at the softer setting, a reflection of the German taste for a generally firmer ride.
Nevertheless, BMW’s engineers have conceived a superbly able and refined chassis which is certainly a contender for the unofficial “Best Car in the World” tag. Despite its electronic elaborations, the 750iL cannot expect to rival a Rolls-Royce in lavish traditional detail; but conversely the Crewe product lacks the springbok abilities of its Munich rival. In recently-tautened Bentley Turbo R form, though, the Rolls-Royce factory does have car which stands square with the other British high-flier, Jaguar, just as the 750iL faces the Mercerdes S-class at home; it is amongst this quartet that this quiet battle will br fought. GC
Development history
The aluminium rendering of Bayerische Motoren Werke’s 60° V12 engine provides such a splendid ensemble that plenty of proud owners must have wondered about displaying its 4988cc in the manner in which so many magazines have photographed it: bonnetless.
First impressions are of a unit far more compact and lightweight (it weighs 529 lb) than Jaguar’s established 5.3-litre 12. This is not surprising as the V12 we assess in today’s BMW flagship is far from being the company’s first attempt at such a configuration. BMW itself publicises the 1926-36 V1 aero engine which was employed in Dornier flying boats, but the relevant point for automotive V12 BMW engines was the M66 programme of the mid-Seventies, which culminated in pre-production units in readiness for 1976. Such V12s could be found in experimental CS coupes, but the company hesitated long enough to realise that the post-fuel crisis world was not ready for a V12.
As I understood it, the BMW V12s of the Seventies were formed from two banks of the six cylinders (323i/320i/520i) debuted in 1977. Such a convenient plan was swiftly abandoned in November 1982, the date on which BMW’s motor engineers started to seriously outline the specification for the V12 we silkily enjoy in 1988. However, the V12 does share the compression ratio and bore and stroke statistics of the slant-six 325i, plus con-rods.
By December 1982 drawing work had begun, a considerable task for an estimated 2500 parts are involved in the current unit. Components were ordered and manufactured from June 1983 onward, and the unit first ran in October of that year. More than 400 units were used in the development programme between September 1983 and December 1986. March 1984 saw the start of test-bed endurance running, but it was January 1986 before the new V12s could be run in a car. A full twelve months were allowed for the V12’s further pre-production development in association with the 7-series it was to power. It is safe to assume that the 6-series coupes have also seen their share of development in readiness for the 1989 coupe 850i.
Sheer performance in terms of output is a by-product of using a 5-litre unit. At 60 bhp per litre and 300 bhp from 4988cc, the BMW is in a slightly hotter stage of tune than Jaguar’s 295 bhp from 5343cc, but BMW’s efficiency— and later design date— extends beyond that facile comparison.
For one of BMW’s priorities, right in line with the philosophy of other leading German car companies, has been to get the performance of the emission control (catalytic convertor) unit on par with non-catalytic convertor units. Politically, clean air is much more important in West Germany than in Britain. The ability to run on unleaded fuel whilst providing suave performance was paramount.
Thus BMW’s nominal selection of 300 bhp as the output from its new 5-litre is better compared with a rival such as Daimler-Benz. In catalytic converter form, the 5547cc V8 within the 560 SEL yields just 279 at 5200 rpm. Jaguar enthusiasts should not laugh. Equipped with the exhaust gas cleanser, Jaguar’s 5.3 droops to 265 bhp at 5000 rpm.
That loss of power on the Jaguar is partially attributable to the loss of its usual May-inspired 12.5:1 cr (11.5:1 in catalytic trim), but BMW is also happy if you make comparisons on the basis of peak torque. For the 8.8:1 cr BMW turns out a muscular 450 Nm (3321b ft) pulling power at 4100 revs, whereas Jaguar can only offer 432 Nm in unleaded fuel form, or less than 400 Nm with catalytic convertor: the 5.6-litre Mercedes yields 430 Nm in catalytic trim. However, both Jaguar and Daimler Benz do have the advantage of lower rpm peaks for maximum torque—Jaguar up to 1100 rpm lower — and the BMW generally has to be delightfully worked through a higher rpm band than its rivals. JW