Bentley Mulsanne Turbo

A unique motoring experience — at a price! 

No fewer than 30 years passed between the introduction of the R-Type Bentley Continental and the subject of this month's Motor Sport colour test, the Bentley Mulsanne turbo; more than a generation during which those offerings marketed behind the Bentley radiator were basically Rolls-Royce models bearing cosmetic alterations. That's not really meant to sound as pejorative as some may take it to be, for we're not dealing with run-of-the-mill machinery in this context; but the fact remains that this policy would have delighted those Rolls-Royce directors who presided when it beat Napier to the post and acquired the assets of the Bentley company as the result of a rather unseemly auction way back in 1931. Immediately after that takeover, the Rolls-Royce company devoted itself to obliterating Bentley's own individual character, a process which continued after 1952 with equal effect, if not with the same premeditated ruthlessness that had characterised the 1931-39 period. The Bentley marque may have had its loyal devotees over the past quarter-century, but since the era of the Continental, mechanically they've had to rely on variations of the Silver Cloud, Silver Shadow and Silver Spirit theme. Now, thanks to the commercial awareness of Rolls-Royce Motors, Bentley individuality is on offer once again with the £61,744 Mulsanne turbo, the first forced-induction machine to carry the winged "B" motif for half a century. 

The Mulsanne Turbo is based on the large, stylish Rolls-Royce Silver Spirit/Bentley Mulsanne model which appeared on the scene at the end of 1980, thus closing the Silver Shadow chapter which had lasted since 1967. With the advent of this new model, some enthusiasts confessed to being a trifle disappointed: instead of endeavouring to take on Jaguar and Mercedes-Benz in the "agility" stakes, Rolls-Royce decided to concentrate on what it knew it could do best. The Silver Spirit and Mulsanne continued the established tradition of high quality, beautifully-built luxury saloons constructed to an impressively high standard. They are quiet, refined and relaxing cars in which to cruise at speed. Unfortunately, in terms of out-and-out performance, the normally aspirated models are not really very fast when it comes to flat-out acceleration: with a 0-60 m.p.h. time in the order of 10 sec. and a top speed of around 116 m.p.h., they were hardly likely to electrify the wealthy businessman used to a Mercedes-Benz 500SEC or a Jaguar XJ12, for all their wonderful craftsmanship. That's where the Mulsanne Turbo comes onto the scene. The addition of an exhaust driver Garrett AiResearch turbocharger to the 6,750 c.c. (104.1 x 99.1 mm.) aluminium alloy V8 engine catapult this two-and-a-half ton luxury saloon into a new performance class. The Bentley Mulsanne Turbo is now a very fast car indeed in a straight line, although it does take some time to get to grips with its sensitive controls, so much so that one's opening impressions of this large four-door sports saloon can be rather misleading.

British Rail's Inter-City service whisked the writer to Crewe in the midst of a depressing early Spring "monsoon"and it was with a degree of trepidation that we nosed out onto a rain-soaked M6, viewing the world from the imperious comfort of the Bentley's leather-trimmed, high-backed seats. The first impression is one of amazing insulation from the outside world, although this changes quite quickly to a worried concern over what seems an excessively soft ride. It is only with time and experience that one comes to appreciate that the Mulsanne Turbo keeps its 235/70VR15 Avon tyres well and truly in contact with the road, notwithstanding initially disconcerting levels of roll, dive and squat.

Of one thing there is no doubt; from the moment one unleashes the car in a straight line, it's clear that this Bentley has no shortage of power. The turbocharger is mounted on the front end of the right hand exhaust manifold and feeds into a Solex 4A1 downdraught carburettor, increasing the V8 engine's power output by about 50% over the normally aspirated Mulsanne. Rolls-Royce has been traditionally reticent in the past over question of quoting engine power output, but the turbocharger installation has, according to the West German type approval papers, helped raise the power output from 198 b.h.p. at 4,000 r.p.m. (DIN) to 298 b.h.p. at 3,800 r.p.m. The turbocharger pressure is limited by a wastegate in the exhaust system, set to open at 7 p.s.i., while throttle lag is kept to a minimum by the provision of a valve to recirculate unwanted air pressure back to the intake side of the compressor in order to keep the turbine spinning when the throttles are closed, a system basically similar to that introduced on Ferrari's Formula 1 V6 turbocharged engines during 1981. Other changes to the engine consequent on the installation of the turbo include inlet and exhaust valves to a revised specification and new strutted pistons to increase the compression ratio from 8.0:1 to 9.0:1. 

In conjunction with all these modifications, the rear axle ratio is geared up from 3.08:1 to 2.7:1 which helps give the car a long-legged gait and also contributes to a slight reduction in fuel consumption over the non-turbocharged model; quite an achievement when one considers the vastly increased power output. 

The turbocharged V8 engine is unobtrusive, but certainly not quiet in the manner of Jaguar's fuel-injected V12-cylinder unit. Under hard acceleration there is a slight amount of induction noise, but generally one is simply aware of a muted rumble from beneath the bonnet. There is some road noise from the large section Avon radial tyres, but when set against the marvellous insulation from bumps, changes of surfaces and ridges, this is minimal and certainly not something that is particularly intrusive.

For sheer performance, however, the Bentley Mulsanne is quite remarkable. Although I would personally not like to run at sustained speeds of more than 100 m.p.h. for very long in conditions of gusting side-winds, the car's straightline acceleration is something to savour. On a pretty damp tarmac surface, and with four adults ensconced within its club-like interior, the Mulsanne Turbo reached 60 m.p.h. from rest in 7.5 sec. and there was no need to resort to building up revs. with the footbrake on and then sliding one's foot fully onto the throttle pedal. It reached 80 m.p.h. in 12 sec. and then surged on to 100 m.p.h. in a fraction more than 18 sec. What's more, there is absolutely no drama whatsoever about the delivery of this remarkable surge of power which, if left unchecked, will continue hurling the car up to and beyond 130 m.p.h. with such contemptuous ease that it really is slightly disarming. The three-speed GM400 automatic transmission deals with the upchanges without any jerking whatsoever, the fact that the unit has changed up merely reflected by a slight "dropping off" in the engine note. Not only does the Mulsanne Turbo knock its normally aspirated stablemate into a cocked hat in terms of sheer performance, but it also beats the much-vaunted Jaguar XJ12 across the board from standstill to 130 m.p.h. Of course, such performance is not exacted without cost and it must be recognised that any owner who squeezes as much as 14 m.p.g. out of the Mulsanne Turbo is probably wasting his time buying one in the first place: even driving with moderation, we could never coax it over 13 m.p.g! 

Coil springs are fitted all round, working at the front in conjunction with lower wishbones, compliant controlled upper levers and telescopic dampers, while semi-trailing arms are fitted at the rear with gas springs used in conjunction with the suspension struts acting as integral dampers and ride height control rams. Once the driver has come to terms with the supple suspension, and learnt to have faith in the ultimate adhesion of this Mulsanne Turbo, despite its rolling gait, this very large saloon can be hustled along at remarkable speeds, even on twisting country roads. 

The power steering is very light, and the large steering wheel endowed with a notably thin rim, but one soon gets into the habit of gripping it delicately and placing the Bentley into corners with considerable confidence. On wet roads you will experience a touch of understeer and if you keep your foot planted firmly on the throttle this will change gently to slight oversteer, even to the point of losing rear wheel adhesion. At first glance, the thought of this two·and-a-half ton car being allowed to slide round the place may be sufficient to give most enthusiasts grey hairs, but a touch of corrective lock brings the Mulsanne Turbo back into line with all the responsiveness of a taut little sports saloon. 

Over deep ripples and bumps on my local lanes, one of which caused Motor Sport's road test Bristol Beaufighter to "bottom out" when approached at 65 m.p.h. with four people aboard, the Mulsanne Turbo rode serenely without any problems. I must say this rather surprised me, because I was convinced that the Bentley rode more softly than the Bristol, although they are both quite similar luxury sporting cars in concept. On dry roads I found myself covering familiar country over secondary roads no less quickly in the Mulsanne Turbo than in my normal staff car, a Capri 2.8i, which is a great fun car on twisting routes and covers the ground with impressive efficiency. That, for me, says a great deal about the way in which the Bentley Mulsanne Turbo has been developed, and while there is no point in pretending that it offers the combination of ride, handling and / or precision provided by Jaguar and Mercedes-Benz, it is far more sure-footed than I would have ever expected. 

Its insulation and internal noise level is far better than either of its two rivals, but I ended up wondering, nonetheless, whether it would have been possible to stiffen up the suspension even further to impart a firmer overall feeling without sacrificing much in the way of ride comfort. That said, the soft ride only really becomes a major problem when one is called upon to change direction suddenly, at high speed or while braking at the same time: under those circumstances the Mulsanne Turbo definitely doesn't feel very secure. 

Braking is tremendously impressive, the four-wheel disc brake set-up covered by two independent hydraulic circuits, each operating a twin piston disc brake caliper assembly on each front wheel and a pair of pistons, housed in a four piston caliper assembly, on each rear wheel. Despite several very firm applications from high speed, the Bentley's brakes never demonstrated any signs of fade or wander, pulling the big car up with incredible precision time after time and proving equally secure in wet conditions despite the fact that there is no anti-lock system incorporated. On the debit side, however, the brakes emitted an irritating squeak throughout the duration of our test, both in wet and dry conditions, which is something one could well do without in a car carrying such a high price tag. 

The interior of the Mulsanne Turbo is, quite simply, a world apart. You enter, rather than get into, this impeccably finished environment through reassuringly thick doors which close behind you with an unobtrusive, but solid, "clunk". Immediately the senses are assailed with the muted fragrance of high-quality leather and, as one glances about, it is clear that the car makers of Crewe are not making any concession to passing trends of styling. The keynote is good, staid, logical taste. Our test car's exterior was finished in a restrained shade of green, complemented by the light tan Connolly leather upholstery: we are told that up to eight matched leather hides can be cut, sewn and fitted to the interior of the Mulsanne in order to guarantee the high level of finish demanded by potential buyers. What's more, the burr walnut veneers which are used to decorate the fascia are matched so that the right side mirrors the left: the Bentley handbook, stating the painfully obvious, also manages to point out that "no two cars have an identical pattern"(!) Beneath one's feet lie deep pile Wilton carpets, trimmed in leather, and there are sheepskin rugs on top of these as well. Just to complete the aura of uncompromising luxury, rear seat passengers are provided with individual sloping footrests on which to place their weary hand-crafted shoes! 

The seats are quite outstanding. I suppose it is possible to argue that a little more lateral support could be appreciated, but I found them splendid in every way. They offer superb comfort, without being excessively firm and the adjustments provided, electrically, by the control on the centre console, enable anybody to find a comfortable position. In addition to the armrests on the doors, there are individual centre armrests for each front seat in addition to well-padded head-rests. Rear seat passengers are catered for with individual reading lights and mirrors and of course, their own inertia reel seat belts, matching those provided for the front seat occupants. 

Through the two-spoke steering wheel the driver is faced by a discreetly labelled 140 m.p.h. (225 k.p.h.) speedometer bearing white lettering and needle on a matt black background and incorporating a mileometer and trip. There is nothing so middle class as a rev counter on this fascia, the matching circular dial to the left of the speedometer taken up by four segments monitoring oil pressure, water temperature, battery charge and fuel contents. There is a small red line two-thirds of the way down the fuel contents gauge marked "Min oil" which indicates the oil level in the sump when a small button to the right of the fascia is pressed. To the left of the driver there is a digital read-out panel including a clock, on-board computer readings and the exterior temperature: if this last-mentioned drops below 2- deg(C), then the "ICE" warning light on the check panel to the left of the fascia lights up to warn the driver of possible impending slippery road conditions. Other warning lights on this rectangular panel include those for the parking brake, brake fluid level, engine overheating, low coolant level, washer fluid level, bulb failure and low fuel level. On the far right of the fascia is the ignition control, below which is fitted a three-position knob to control sidelights and headlights. Windscreen wipers are controlled by a similar switch on an auxilary panel a little further down, leaving the steering column controls to deal with gear selection for the automatic 'box (right) and indicators (left). The parking brake is foot operated with a release lever behind the fascia and the lights are dipped by means of a good old traditional "on-off" foot switch which makes a pleasant change from most cars that come our way these days.

The automatic split-level heating and air conditioning system is controlled by two rotating dials mounted on the secondary panel below the main fascia to the left of the steering column, and the entire system functions with impressive promptness. This was one of the few cars in which it was possible to channel warm air onto one's feet and cool air onto one's face without any undue drama or difficulty. the radio / stereo system was first class, as one would expect, and the only minor operational problems related to the central locking system's reluctance to respond to turning the driver's door key on every occasion: sometimes the door locks would depress, sometimes they wouldn't. The driver's also has master controls for operating the electric windows while there are individual controls on the other three doors.

The large bonnet swings forward to reveal the daunting mechanical package beneath, not a proposition for home maintenance by any standards, while the capacious, carpet-lined boot houses the Bentley's spare wheel beneath the floor and provides a generous tool kit which is fitted on a special tray. The fuel filler for the 23.5 Imp. gallon fuel tank is mounted behind a panel on the rear nearside waistline and can be opened by pressing a discreet little button on the fascia. At an overall average consumption of slightly less than 12 m.p.g., a full tank of petrol would last about 270 miles.

Distinguished visually from its normally aspirated counterpart, the Mulsanne Turbo sports a radiator shell painted to match the rest of the car's bodywork: from a purely personal point of view I would have preferred the normal, unpainted, radiator, but then these things are all subjective. . . . Right near the end of the car's spell in our hands a worrying high-speed misfire developed, and this was eventually traced to a faulty sparking plug on the Mulsanne Turbo's return to Crewe. That was the only mechanical blot on this Bentley's copybook, an unfortunate minor footnote to an otherwise trouble-free week's motoring.

As we mentioned earlier, the Mulsanne Turbo's price is £61,743.50 of which £4,130 is car tax and £8,053.50 the dreaded VAT, so our Government will doubtless be happy to see as many of these Bentley's sold as possible! Just in case you think that might be all, we should mention that there is a range of additional equipment for this car ranging from Fiamm Avanti air horns, operated by a foot switch (£187.50), through to a non-standard paint finish (presumably of one's choice) at £720.41. All of which leads us to the ultimate question —​ is it actually worth the money?

Assessed purely as a motor car against its significantly less expensive rivals, it must be questionable as to whether the Mulsanne Turbo can justify its price tag. However, for the well-heeled connoiseur, who has the means to finance this sort of outlay, who prides himself on impeccable taste and appreciates near-flawless standards of finish and refinement, it probably is. There are certainly other luxury cars that deliver comparable performance allied to better overall handling, but there is nothing, in my experience, that delivers these qualities in the same distinguished, haughtily upper-crust, and oh-so-British style as this turbocharged Bentley saloon. — A.H.