FOR more than a decade the cornerstone of BMW's sporting image has been its imposingly styled big coupes; the angular, yet stylish, CS-series giving way in 1977 to the more rounded 6-series range which continues' to captivate and entertain enthusiastic owners into the 1980s. When the original 633CSi was supplemented in 1978 by a larger-engined sister, the 635CSi, we enthused over this refined, extremely well equipped and very fast product from the German manufacturer. Now, four years later, we have reac muainted ourselves with the latest 635 derivative. Outwardly it remains alin't unchanged, bearing virtually no visual testimony It the enormous amount of development work which has resulted in it becoming a significantly vote efficient overall package while at the same ! sustaining its sporting appeal. In fact, that last observation does the 635CSi slightly less than 'MI credit: in many areas its performance has been ntproved over the old model, the car is lighter and it 'swore economical. A policy of continuing ....del improvement has not resulted in a drasticallY revamped Profile, but merely a much ref,'
led interpretation of an existing popular line. Although it has been available on the British market for the last five years, familiarity certainly hasn't bred contempt for this coupe. By any stan 'dards the 635CSi remains an imposing, even strik, -.8, machine. It is a big car, well PrulPortioned and well balanced, from its lengthy, gen!IY sloping bonnet incorporating the eduistt-o""Ifcfttiaivel. cavreiiwrhcicalh segraildoem, sfoailsittso stuharjalny interested brad in traffic although it manages to avoid some of the vulgar excess ePit°mised by that 3.3-litre CSL "batmobileof the nod-seventies. The heart of the 635CS1 remains its taut single overhead camshaft six-cylinder engine which has served BMW extremely well in a variety of different forms from 2.5-litres to 3.5-litres since the late 1960s. The bore and stroke has been slightly revised in this latest coupe, the dimensions now being 92 mm. x 86 mm. for a total capacity of 3,430 c.c. (previously 93.4 mm. x 84.0 mm. for 3,453 c.c.). Quoted power outputs remain the same: 218 b.h.p. at 5,200 r.p.m. and, thanks to painstaking weight-saving efforts, the 635 is now more than 170 lb. lighter than it was when first introduced. This smooth, taut power unit is further enhanced by the fitting of Bosch Motronic and fuel
injection control system with the over-run fuel cut-out which was first offered by BMW on the 733i. The fuel cut-out comes into operation when the throttle is closed at engine speeds over 1,200 r.p.m., and provides a significant upsurge in the coupe's economy. From a handling point of view the car is sensitive and responsive, although it definitely calls for respect on wet surfaces. In contrast to the 635CSi which I tested for our sister publication Motoring News late in 1978, the latest model has excellent braking performance. I'm not simply referring to the qualities offered by the standard ABS braking system, but to the fact that the large servo-assisted disc set-up displayed no signs of fade during the course of the week's test. A happy
this point the 635 lets you know that the work beneath the bonnet is being carried out by a six cylinder unit rather than a V8 or a twelve. Right through the performance range, the latest 635CSi is fractionally, yet consistently, quicker than its predecessor. BMW's claim to a top speed of 142 m.p.h. seems quite acceptable, even though we never found sufficient room to reproduce that during the course of our test. However, considering the unflurried way in which it topped 125 m.p.h., allied to its rock-solid feel at that speed, there seems no reason to question their claim which places the new car 5 m.p.h. quicker than the older model. An improvement in 0-60 m.p.h. time from 8.7 sec. to 7.1 sec. is representative of the 635's better acceleration throughout its performance range and particularly noteworthy is the way in which it covers the ground between, say, 80 and 110 m.p.h. in third and fourth gears.
Internally, the BMW 635CSi continues in a reassuringly familiar vein, minor improvements rather than major changes being the keynote. Instrumentation and positioning of minor controls is, as always, beyond reproach, although the tallest of drivers may find that he has to lean forward ever so slightly to make sure that the first gear is engaged. Gearchange movement is pleasant, although the throw is rather long, and it is occasionally possible to snag the overdrive fifth (dog-legged away from the driver to the right) when you're actually seeking third. The clutch engages smoothly and undramatically, with no sudden snatching of any sort.
Through the upper half of the pleasantly thickrimmed three-spoke steering wheel, the large speedometer and matching rev. counter remain clearly visible and reflection free, separated by the water temperature gauge, the fuel contents gauge and thc bank of service indicator lights, a system which was pioneered on the new 5-series range. Whether you like snobs system or not depends on one's personal point of view, ai does a preference for fuel economy gauges and sophisticated on-hoard computers which can produce calculations between time, distance, speed and fuel consumption, such as the one fitted as standard to this 635. I may well be at odds with the majority of my colleagues in my personal opinion of these accessories, burl have to confess, Perhaps slightly ruefully, that I took only a Passing interest in the computer. It is very informative to have all these pieces of information at one's finger tips, but I will contend to my dying day that while they can certainly assist the car's 0Perating efficiency, they in no way enhance its safety. I, for one, hope that I will not be wasting my time watching such a gunmick as I sail into the back of a stationary bus, my attention diverted from the normal business of studying the road ahead. I prefer to enjoy driving such machines as the 635 to the full, putting in the petrol and then finding myself pleasantly surprised when 1 calculate the overall fuel consumption. That's the ultimate testimony to the progress BMW has made with its electronic control systems: an average of 24.1 m.p.g. during the course of our test would not have been dreamt of from the old 3.3-litre CSi!
Having said all that, I am an admirer of the BMW "check panel" (situated to the right of the 635's tascia; by which, at the press of a single button, the driver can be informed in advance of any potential problem concerning lights, fluid levels and the condition of the brake pads. The steering column is adjustable for reach, end this, in conjunction with swat which can be
adjusted fore and aft, tilted, raised up or dropped down, means that one would have to be an awkward shape indeed to be unable to find a comfortable driving position. The seats are deep and firm, upholstered either in leather or cloth for the same cost, depending on the individual customer's choice. Visibility is fine from every angle, relatively slim pillars meaning that there are no blind spots worth talking about. Windows are electrically controlled, of course, with the driver having a master switch atlas side by means of which he can isolate the individual controls of the rear side windows, thereby preventing mischievous little passengers from attempting to amputate their own hands in a fit of youthful curiosity.
I have always considered BMW heating and ventilation systems to be excellent, but that fitted to the 635 is further improved by a pre-set facility by which a temperature can be selected and temperature sensors and the thermostat get on with the business of controlling that temperature until an alternative is selected. There is plenty of ram air effect from the vents on top of the fascia and the fan works quietly when its assistance is needed.
It goes without saying that paint finish and trim levels are of a very high order, and 635 standard equipment includes an electrically operated sliding roof which can also be made to tilt forward. There is very lirde in the way of obtrusive wind noise or unruly buffeting when the roof is fully opened, due in no small part to the deflector which flips up at the front as the roof slides back. The effective four-headlight set-up is kept clean by powerful wash / wipers activated from a steering column stalk, there is a central locking system, and a splendid Blaupunkt stereo radio / cassette player is also provided.
To sum up, the revised BMW 635CSi is essentially a civilised grand tourer which refines a ten-year-old concept to fresh levels of sophistication. For those who don't want to pay £22,950 for the privilege of experiencing 635 motoring, they can opt for the more modest 628CSi at £17,895 if they don't mind putting up with rather less in the may of out-and-out performance and some of the creature comforts. In an exalted, highly competitive sector of the market the 635CSi faces such mouth-watering competition as the Jaguar XJS HE (£19,708), the Porsche 928 (£21,827) and the splendid Mercedes-Benz 380SEC (£25,700). Hand on heart, I would had it impossible to make a choice, although the time spent pondering such a problem, assuming the money was incidental, would be quite delightful. — A.H.