Mercedes W123 continues the quest for refinement

Mercedes today is even more impressive than the list of engineering achievements from the past would make you expect. The gleaming premises at Untertfirkheim ripple with the strength of prosperity that comes as the culmination of the years spent producing. honest contenders for the title of "The Best" in fields as varied as passenger cars, aero and marine engines, trucks and modern gas. turbines. The goal always seems to be the same, thoroughbred engineering to a standard that rivals will have to acknowledge, often before trying to emulate the efforts of Daimler Benz. This search for the best in engineering technique and reliability does not preclude the possibility of mistakes of course. Here the writer is tempted toward the view that the big 600 Grosser series has been a failure; compared in commercial terms to Rolls-Royce. However, when talking of passenger cars between 2 and 6.9-litres in less exotic plumage, which are produced at the rate of over 350,000 per annum, it is hard to fault the company's business acumen or engineering integrity. The latest addition to the Mercedes-Benz line is the W123 coded-car range, which we were recently able to drive for ourselves in Germany.

The W123 series stretches over Seven models in British RHD form, the cars having been available in Germany since the beginning of the year. Displaying that engineering expertise of which we talked, the same basic car concept is powered by everything from 2-litre four-cylinder petrol and diesel motors, to a 3-litre five-cylinder diesel and a six-cylinder, d.o.h.c. petrol engine of 2.8-litres, which features mechanical fuel injection. In Britain prices begin at £4,939.74 and escalate to £7,989.93, the four-cylinder petrol engine of 94 DIN brake horsepower initiating the range and the 177 b.h.p. six representing the peak. As before, the model designations are almost self-explanatory: the marque number giving cubic capacity when the nought is removed, viz 200, 230, 250 and 280E for the petrol engined cars. Mercedes stick with Einsprintz for injection, instead of anglicising in the BMW 320i manner. The diesels simply carry the suffix D, covering 200, 240 and 300 models.

Those with sporting instincts will find that Mercedes fit automatic transmission on all but 2-litre models destined for the UK. Although I am sure that those who buy a Mercedes are not deterred much by price (the British end of the company are having to delay some 35 coupe customers in the £13,000-plus bracket until next spring, and they already sell 30 such cars a month) it does pay to watch the option list carefully on price.

When you start development, as Mercedes-Benz did, with an already acclaimed range of cars, it becomes a very much harder task to offer tangible improvements. From both the public and enthusiast driver viewpoint they did succeed, and the new ears do offer higher standards of noise insulation and safety with no weight increases. A laudable achievement indeed in these days of obese battering rams that are ideally suited for hitting bridge parapets, but not for driving response. Some might put the improvements in roadholding under the safety banner too, and here the cars do show appreciable improvements over the previous "New Generation" models. Incidentally the company has Sold 1.8 million examples of the latter series, but with the workforce at Sindelfingen producing (with aid of considerable, sensible, mechanisation) 800 W123 types a day, it cannot be very long before the previous series is dropped following a good eight-year innings.

One companion commented that Mercedes always start the design of a new car with a really clean sheet of paper, no inherited concepts need stand in the way of a Research and Development staff that number 3,500 personnel. Nevertheless, our companion continued, "they always end up with a car that looks the same, just like a Mercedes!". In fact a slide projection of the model changes in Mercedes' cheaper (comparative term) range does show how the lines have altered from gently bulbous, through angular severity to the present slight wedge profile. What most of us are bound to notice is the new headlamp and frontal styling, the distinctive W123 larger outer headlamp applied on all models, except 280E, which really does look like an S class model at first glance.

Mercedes safety work dates back 40 years, so it was interesting to see that they have now progressed to the point where they impact test individual chassis components and sub-assemblies. They have used this data not only to improve items like roll-over crash damage resistance, but also to lighten and strengthen the body, so that they do not pay a weight penalty every time an improvement in accident behaviour is registered. From a structural viewpoint the movement of the petrol tank to a new home over the axle is a major change. I was more intrigued that the adoption of parallel wipers had improved vision for a l.h.d. car considerably: I hope we feel the benefit for r.h.d. pilots too, and that Lancia copy the idea as quickly as practicable!

Wheelbase of the W123 series is increased by 1.77 in., to a total of 110 in., which lies within an overall length of 186 in. There is a distinct bias toward narrow rear track, tile front now measuring 58.6 in. (up 1 1/2 in.), and the rear 56.9 in. overall body width is 70.3 in. and the height 56.6 in. Weight varies quite Sharply according to the model the 280E carrying 28.7 cwt., the 250 is some 200 lb. lighter at 26.7 cwt. and the basic fourcylinder saves another 44lb.

More significant for a roadholding improvement is the adoption of double-arm S class front suspension units, suitably adapted for new body weights. This front suspension features long shock-absorber units, a separate, slightly tilted-forward Coil spring, anti-roll bar and complex anti-dive geometry. That combination, with zero offset steering alignment, produces a new standard Of production car handling and ride characteristics from conventional components. Rear suspension is substantially unaltered, based around trailing arm principles with low pivot Point geometry, an anti-roll bar, and combined coil spring/. telescopic damper units. These have additional rubber springs incorporated OS at the front end) to further reline the ride quality in a "helper" role.

Power steering around the company's recirculating ball system is a more widely adopted feature in the new range: only the basic 200D will not have power assistance in the UK. A superb four-wheel disc braking system is improved in that a level indicator for pad wear is incorporated, along with plastic sheaths to protect the brake pipes against damage at vulnerable points.

While the transmissions remain unaltered in themselves,a four-speed gearbox being offered in manual and -automatic form, the engines have important modifications. First is a new, larger bore, version of the old 230.6 motor sporting tour main hearings and nine counterweights. Now the bore is 86 mm. by 72.45 mm. stroke, the ensuing 2,525 c.c. producing 129 b.h.p. at 5,500 r.p.m. with the aid of a single four-choke Solex 4AI. and an 8.7-to-1 c.r.

Servicing needs have been given heed throughout the range, the bonnet opening to right-angles now; the engines incorporating a socket to allow the use of electronic diagnostic equipment, and a Ferrolastie head gasket is now fitted that eliminates the need for 40 minutes head tightening procedures at the first service. Provision is also Made for withdrawing the oil through the engine oil dipstick orifice, though this could be a mixed blessing if special equipment is needed. For the 280E the engineers have abandoned electronic fuel injection and opted for their own mechanical layout as introduced on the 6.9 450 SEL.

Daimler Benz had devised a 22.7-mile test route with infinite care, to include everything from bumpy country lane to a short stint on the motorway. I drove four models—the petrol 200, 250 and 280E (three-up) and the fascinating five-cylinder 3000. All of the cars showed outstanding road manners in respect of ride quality and progressive braking safety, no matter how pushed. All shared the single pane instrumentation viewing screen, which Rover initiated, and BMW further endorsed, before Ford and Opel spread such clear instrumentation to the masses. All showed standards of finish that one demands of the three-pointed star. The materials are not exotic, but the plastics are stout, accurately positioned and unmarred by the common "phantom glue spreader", or his friend, "the absent locating affixer", who provide such merry shouts of glee when the trim starts dropping on your lap from lesser marques. The Mercedes theme is very understated, a German passion at present which converts large expenditure into quiet sobriety.

Of the cars 1 drove; I preferred the manual transmission 250. 'Ellis combined a marvellous balance between power, cornering capability and braking, fed into one's hands by a beautifully "weighted" power steering. The bodywork offers wind noise buffeting a minimum of assistance, and the new six-cylinder shows this tranquillity to great advantage. You can still hear the engine working, but neither that nor pressing on over indifferent roads is likely to make the owner Of this Mercedes in the least fatigued. 011 the motorway the car showed the equivalent of 117.9 M.p.h. and the gear speeds of 31, 50 and 86.9 m.p.h., marked on the speedometer, proved a good guide to extracting the best. performance.

The 280E was dampened down by three bodies and some interesting conversation that distracted me from enjoying the car to the full. I did catch the automatic out on occasion, for it is very sensitive to throttle pressure, and it actually changed down two ratios in succession, paused fractionally for thought and seemed to be caught in neutral! In the role of business express I could hear conversation quite happily at 105 m.p.h. and the speedometer registered the 124.2 m.p.h. claimed for the manual version readily.

The 200 was interesting for mere mortals like ourselves, for its sub-£5,000 pricing has not removed the single-finger gear-change operation, or the clever removal of vibrations that would characterise most four-cylinder cars at a constant 100 m.p.h. Naturally there is engine noise at this speed, but at 70-80 m.p.h. the 200 is a very nice way of travelling. Obviously there is a lack of acceleration compared with the 280E back-to-back (Mercedes quote 0-62 m.p.h. in 15.2 and 9.9 sec. respectively) but there is always the thought of fuel economy, which can reach 31.4 m.p.g. according to Mercedes figures. Interesting to note that the 200, the 300D, 250 and 280E are all quoted as returning between 22 and 26 m.p.g. at cruising speed fractionally short of 70 m.p.h., the five-cylinder diesel being the most economical.

Finally there was the 300D. My colleague A.H. of F1 reporting repute thought I was being very silly when I suggested that this was a triumph of engineering, taming and refining the diesel for passenger car use (as Mercedes feel they must in view of impending American emission/m.p.g. legislation). As a party trick I persuaded him to stay in 4th gear and drop virtually to a standstill on a convenient incline. Even he was impressed by the way the big saloon clawed its way uphill, running smoothly upward from 18.6 m.p.h.! To drive, the big diesel feels completely flat until pulling through 4th gear, when you realise that it will honestly exceed 90 m.p.h.

In conclusion I can say that the quiet but worthwhile advances made in the WI23 range typify why Daimler Benz was the only manufacturer to increase in popularity through the fuel crisis. They may be conservative in their ways today—it is hard to imagine that this is the same company that produced those fierce flamboyant sports cars of yore, and even harder to imagine them racing again—but there is no doubting the success of these conservatives.—J.W.