Road Impressions

The Sunbeam Rapier H120 and The Auto-Union Audi 100LS

Two Interesting Closed Cars with High-Efficiency 1.7-litre Engines and Similar Performance—Both in the £1,500 Price Bracket

Comparisions are said to be odious and we do not regularly make a practice of lining up similar cars that have come to us for assessment. However, moving out of the family-car price class, there is growing interest in the semi-luxury closed car which sells for abound £1,500. There is no denying that by just about doubling the amount paid for a medium-sized closed car very much higher motoring standards are arrived at. In this now popular price-class the Rover 2000TC and the Triumph 2.5 PI are well-known and have been adequately covered in Motor Sport. There are two more cars of this kind which merit attention, Rootes’ Sunbeam Rapier fastback in H120 form and the Auto-Union Audi 100LS, which is a Mercedes-Benz-engineered product of a Company now owned by Volkswagenwerk with N.S.U. having recently put a finger in this particular pie.

They are comparable cars, both having push-rod o.h.v. engined of 1.7-litres swept volume, off high-efficiency type, and their prices being within £29 of one another, the German car being the less expensive in spite of Import Duty. Comparable up to a point, that is, because the Sunbeam is the more sporting proposition, with fastback four-seater two-door body and the latest Audi more of a touring saloon, very spacious indeed for a car of this size, with four doors. Both aim at the 2-litre class, although giving away cubic capacity in this respect. The Sunbeam and the Audi engine both have five main bearings; the published weights of the two cars are, respectively, 20.5 cwt. and 20.6 cwt.

We reported on the Sunbeam Rapier fastback in our issue of May 1968, and the change in the H120 centres around the Holbay-tuned Weber-carburetted power unit. This has an alloy cylinder head (as on the normal Rapier), twin side-draught Weber 40DCOE carburettors in place of Zenith/Stromberg, and the expected improvements to ports, pistons, valves and valve gear. The c.r. is up to 9.6 to 1 and there is a four-branch exhaust system. This 1,725-c.c., almost square (81.5 x 82.5 mm.), engine is giving 105 b.h.p. net, at 5,200 r.p.m. Audi have used a Mercedes-inspired power unit since the take-over but formerly in body shells adapted from the old range of two-stroke cars. The 100LS is entirely new but the engine follows the four-stroke Audi pattern in having a high-efficiency swirl induction system and special combustion chambers permitting a c.r. as high as 10.2 to 1. It is a longer stroke engine than the Sunbeam’s, 81.5 x 84.4 mm., giving a capacity of 1,760 c.c. A single downdraught Solex 32TDID carburettor suffices and the power output is quoted as 115 b.h.p. at 5,500 r.p.m., but this is S.A.E. measured, so there cannot be much difference between these Holbay and Mercedes units.

Rootes use a bigger diameter clutch, stronger clutch springs and a higher axle ratio—3.89 to 1 against 4.22 to 1—to cope with the increased power which Holbay Racing Engines have given them. They did not consider any change in the standard Rapier brakes, which are servo-assisted disc/drum, or to be suspension, was merited.

The Audi 100LS is an entirely revised car, lower, longer and wider than the Super 90, with new strut and coil-type double wishbone i.f.s. instead of longitudinal torsion bars, this lowering the car and improving the handling. To further assist in the lowering process, the body incorporates a central tunnel in which live the control runs and exhaust pipe. You step down into an Audi, on to a durably carpeted floor. The Audi is quite different form the Rapier in being a front-wheel-drive car, with inboard front disc brakes and a “dead” back axle on transverse torsion bars. The Sunbeam is sprung on MacPherson struts, coil-springs and lower wishbones at the front and its live back axle is on semi-elliptic leaf-springs. Whereas the Rapier uses recirculating ball steering, the Audi has rack-and-pinion. Both cars have central floor gear-levers, the Rapier’s supplemented by their usual overdrive operating in 3rd and top gears, cancelling if the lever goes through neutral, and o/d. ratio being 0.80 to 1. It is interesting that Audi in Germany offer the car with a steering-column gear-lever, which for years I disliked on these and D.K.W. cars, but Mercedes-Benz in this country, who market Auto-Unions, fit the optional floor lever on r.h.d. models.

I do not know that the respective dimensions of the two cars are of much interest, but the Rapier has a wheelbase of 8 ft. 2½ in., the Audi’s wheelbase in 100LS form measures 8 ft. 9.3 in.

Performancewise, the two cars remain in close harmony. The Rapier H120, with nearly a 20% improvement in power and torque, will reach a top speed of 105 m.p.h. or a shade more in o/d. top gear, and will get to 60 m.p.h. from rest in 11 sec. The Audi 100LS is good for a maximum of 106 m.p.h. and is 0.8 sec. less rapid to 60 m.p.h. The Rapier looks the faster car, not only because off its fastback styling but because in H120 form it comes with “speed stripes” along the sides and is on sculptured 5J x 13 Dunlop wheels. The Audi is quite plain, but handsome, in comparison, the test car being in a most attractive shade of dark green.

Having dealt previously with the fastback Rapier, I will confine myself to remarking that personally I do not like its appearance—too much glass, perhaps, wheels that are too small?—but that it served me admirably for some 1,200 miles. It is a reasonable four-seater in spite of the drop roof, has comfortable seats with reclining squabs, and well-placed controls. The instrumentation is very thorough, with lots of dials to read, the idea being that if all is mechanically healthy the needles of the oil-pressure, oil-temperature and water-temperature gauges lie roughly upright. This implies that there is about 40 lb. pressure, that the oil is at 80° F. and the water heat o.k. The cubby lid is ridiculously difficult to open, maybe because its grip has been deleted in the interests of safety.

The Holbay engine is delightfully responsive, but the Webers do not open up as smoothly as on other engines. In spite of the increased power the engine, which uses red segments on the tachometer from 6,000 to 7,000 r.p.m., will run remarkably slowly. By judicious use of o/d. I coaxed 25.6 m.p.g. of four-star fuel from it and at the end of my stint the sump needed rather more than a quart of oil, equal to roughly 600 m.p.p.

This Rapier is pleasant to drive, even if the road-holding has dated somewhat, with the current understeer tendency allied to a little leniency of back axle movement. The brakes are good, the Dunlop SP68 tyres held well, and the happy impression is of a very fully-equipped car which has modern ventilation, an unusual body, is nicely finished, as a nice gear-change, and handles adequately.

Incidentally, both cars have inclined engines to lower the bonnet line, that on the Rapier being at 15°, the Audi’s at 40°.

If the Sunbeam Rapier is a luxury-equipped car the Auto-Union Audi is equally so. It has some very sensible items, like finger-tip washers and temporary wipers’ control from the r.h. multiple-purpose control stalk, vizors cut away so as not to disturb the rear-view mirror, high-grade keys, including a tiny one for the petrol filler lock, seats which are part leather but mainly upholstered in cloth (all cloth for the wide bench back seat), which gives you the best appearance of two types at the expense of some clothes cling, and easily adjusted rear squabs to the big, somewhat hard, front seats.

The main appeal of this Audi is the amount you can get into it, human and inert. The luggage boot is huge, 23 cu. ft., illuminated and self-locking. The interior of the body is in proportion. There is comprehensive ventilation, with facia vents set low and consequently not vulnerable to sensitive eyes, hot-air vents for side-window demisting, and cleverly contrived heater controls, on the centre of the uncluttered facia, giving easy selection and dividing requirements of passenger from driver. The interior stowage is thorough—a drop well in the facia, two big open under-facia shelves, wells in the front doors and two stowage recesses on the gear-lever tunnel, the plated surrounds of which reflect badly in the windscreen in certain lights.

The 1.7-litre engine gives the impression of being a willing worker, at the expense of some clamour when accelerating and a bit of a zizz while cruising in top gear. But it gets this big medium-capacity car along very quickly, and the gear ratios are well spaced, 3rd being a useful overtaking gear, to well beyond the British top speed limit. The gaitered gear-lever, with leather-covered knob, controls a change which is rather sticky, with very strong spring-loading towards the higher ratios.

The supple springing of the Audi becomes a disadvantage when it has to be driven fast, as I discovered in trying to keep ahead of a Ford Cortina GT on the winding road from Tonbridge towards Edenbridge. The car develops an unpleasant lurchy oversteer when cornered fast, although the front-drive pulls it round, and the Continental tyres remain discreetly silent. The soft suspension is also evident when heavy loads are carried in the huge boot, as the handling not only deteriorates, but the headlamps illuminate the tree tops. I drove for four hours almost entirely on dipped headlamps for this reason, one memorably tiring night. With normal loads the lamps provide good illumination and when the ignition is cut they are automatically switched off, preventing the car being parked, headlamps ablaze, by thoughtless drivers. The gear-change from 3rd to 2nd is really rather horrid. Reverse gear is well guarded, the know having to be depressed and pushed across the gate and forward to engage it.

As on the Sunbeam, the brakes are servo-assisted disc/drum. At first they seem spongy but prolonged fast driving brings respect for them. The hand-brake is nicely recessed between the seats. Push-buttons on the facia look after lamps, hazard warning, and additional wiper selection, the latter first giving full speed, then half speed.

The steering is low geared and not especially accurate, but it is light and has quick castor return. Steering snatch is transmitted on full lock. Even in 2nd gear the transmission can snatch if over-eager opening-up is indulged in. Corners can be swept round with Continental 165 SR14 radials looking after sticktion, the angle of lean notably flat. But, as I have said, this is more of a fast touring than a sporting automobile, with a comfortable, well-damped, but somewhat soggy ride. It is nicely effortless on long journeys; its very high-class typically Germanic finish and full equipment is a source of pleasure. As for range, I had gone 355 miles from the Auto-Union headquarters at Brentford before the very low reading of the petrol gauge induced me to refuel. It seems likely that several more miles would have been possible, but that is an excellent fill-up for a saloon car. But the Rapier did even better—373 miles, full to dry tank. The tank capacities are quoted as: Sunbeam 15 gallons; Audi 12.8 gallons.

Subsequent experimenting showed that this high-compression Audi is notably light on fuel, giving 28.7 m.p.g.; I used four-star as instructed and it pinked only if really allowed to slog in a high cog. Oil consumption came to 600 m.p.p. Ventilation of the big body is thorough, too, the claim being that all the air in the passenger compartment is changed every 15 sec. at 60 m.p.h. Erik Johnson tells me that Audi’s Sales Training Officer, Bill Hintze, demonstrated how safe is the 100LS’s structure by indulging in a multiple accident on the motorway, when he was shunted from rest by a 3-ton lorry into other cars. I omitted to include this sort of thing in the Motor Sport test, but it is nice to know that Hintze was uninjured. . . .

Audi instrumentation consists of a 130-m.p.h. speedometer with total and decimal-trip mileometers, a matching dial for fuel contents and water heat, the latter reminding me that the high-efficiency engine runs efficiently hot, as close to 90° C., and a noisy Vdo clock, on an African-wood facia. A further small “dial” was occupied on the test car by a diagram of gear locations. The bumpers are fully rubber-tipped, and an anti-dazzle mirror and good vizors are fitted. The big, low-set steering wheel is now round instead of oval and an African-wood spoke sounds the horn. The Bavarian factory at Ingolstadt is turning out about 230 Audis of this sort a day; Rootes are dependent on the supply of Holbay engines where the Rapier H120 is concerned. The H120 was announced last autumn, the 100LS last April.

So there it is. In spite of their similar engine size, price, and performance, there two cars, one as typically British as the other is typically German, are not really comparable. Which relieves me of having to tell you which one I would personally prefer to own!—W. B.