Driving Impressions

VW’s 200 m.p.h. diesel

47 m.p.g. at a constant 155 m.p.h.

The object at my damp feet looked more like a stranded missile than a car, though its cowled-in wheels and front aerodynamic tabs were missing after recent months spent posing at shows. In its natural element, the Nardo test track of Southern Italy, this VW project —  the ARVW, or Aerodynamic Research VW — a 16 ft. plus projectile, made such effective use of its turbocharged ex-LT van diesel that eight diesel world records (many belonging to Mercedes Benz) were broken. The slowest speed record attained was that for a standing 10 kilometres (150.20 m.p.h.) while the fastest single lap during several days, culminating over 1 1/2 years’ hard work, was 224.85 m.p.h. Significantly the one hour period, where the ARVW could work to its designed limit of 5,000 r.p.m. in the fourth of four converted Audi 100 ratios, brought the highest official record (219.47 m.p.h.).

Ehra Lessien, the huge VW test track hard up to the border with Eastern Germany, was the site chosen for us to drive the intriguing chain drive (x2 of 20 links apiece) VW, but conditions were such that we did little more than discover that first gear truly was worth 62 m.p.h. and find the extraordinary pulling power at 1,000 r.p.m. in fourth.

Work started on ARVW in September 1979 with the brief of reducing drag coefficient (Cd) to a minimum while operating a fuel efficient engine and stable body. Project leader Dipl. lng. Jurgen Nitz, a young man with an affection for the original Jaguar E-Type, was appointed project leader and it was he who guided us. Overall responsibility for 600 research and 5,000 development engineers is that of the seven-league boot equipped Dr. Ulrich Seiffert, who was the gentleman who spotted that our modest height would best fit into this 32.95″ tall machine with its glider-modelled cockpit.

Nitz told us, “the body really was born in a wind tunnel.” The orginal work with wood and styro-plastic models was done at Wolfsburg, but once they were satisfied with the shape, Bauknecht produced the fibreglass reinforced plastic bodies and some detail work for two cars. Overall length of the final version was 196.85″; width some 44.56″ wide (resting on a miniscule 25.59″ track, half that of a Ford Escort or a Golf) and supported on a 98.42″ wheelbase, a couple of inches shorter than you would find for the current Capri.

Apart from fitting in the configuration of a mid-engine, 28.58 gallons of diesel (in tanks either side of the driver), and all the associated cooling and transmission systems, VW were obliged to consider the height of any potential driver and the use of 15″ diameter BBS wheels. They carried Pirelli tyres, because this company was the only one sufficiently interested to offer a special low rolling resistance slick, compounded especially for this vehicle and track.

The result was a long, thin, tube. Much in the tradition of previous record breakers you might say, save that they had to insert another 10 mm. (nearly 4″) to accommodate even a shorty such as myself during the early design stages. Also disimilar to many record breakers was the wide use of production mechanical parts and the complete driving ability of the finished product. Of course, it rolled heavily with such a narrow track measurement — even with coil springs that our body weight could not begin to compress — but the braking and 1,000 r.p.m. full throttle, fourth gear, flexibility were outstanding memories of a car that even steered and re-started in much the same way as a production car: obviously too much lock, too quickly, was going to upset the silver apfel-wagen but even my gross inputs, over 2-3″ of standing water, left the vehicle pointing straight ahead, and the driver wishing that something more sporting than 2,000 r.p.m. in third could be realised without the car slipping any further sideways.

Under the sleek body, with its perspex cowls for aircraft landing lights (giving illumination superior to that of some rally cars, despite the cowling and use of only two 100 watt units) and cockpit, there is an oxygen welded aluminium frame. This has some stressed panels, especially around the safety fuel tanks. The tubing is used to run both front and rear roll-over hoops, as well as the input and output cooling sides of the front Behr water radiator.

The in-line six is boosted to a maximum 0.86 bar via a single KKK tubocharger and the charge is water injected instead of intercooled in the interests of lessening aerodynamic drag. The only air feed in the side of the body is necessary to control temperatures in the turbocharger area.

Mahle pistons operate a 16:1 c.r. — standard LT van is 23:1 — after enlarging the alloy head’s swirl chambers. A specially made Goetze gasket was also necessary, as was the old diesel trick of spraying the piston undersides with oil. The camshaft remained standard, thus the extraordinary flexibility in association with recalibrated Bosch injection.

The results? A maximum 175 b.h.p. at 4,700 r.p.m., with some 217 lb. ft. of torque at 4,100 r.p.m. to move the 2,310 lb. machine with its remarkable 0.15 drag factor. In fact the original models lacked the front tabs, just as in our test, and they recorded 0.13 Cd. Consider that Ford and VW have been involved in some spirited German argument over factors of 0.42 for the Golf and allegedly for the Ford Escort (which is claimed to have a factor 0.385 in normal trim or 0.375 in XR3 guise) and you begin to appreciate the radical results VW have achieved with what is a moving research machine, not a theoretical model.

There is an awful lot more of technical interest within the ARVW, but not space to elaborate. How does it feel to drive?

Tantalising, in a word. A sheet of water, varying in depth from tenths of an inch to several inches almost prevented our driving the car at all. The 195/50 P7s could not have had a tougher task, especially with no front tabs and such a narrow track.

VW decided to trust us. Hurriedly I crammed myself into the unpadded cloth “seat”, threading my legs through warm alloy tubing to reach the conventional foot controls, which include a brace to the left of the clutch. Cockpit details include six dials. One is a 5,500 r.p.m. tachometer of the same unobtrusive black and white dial design as the supporting instrumentation which covers engine, intake and transmission temperatures, as well as oil pressure and boost (the most we registered was 0.6 bar).

I had time to note that a golfball gearlever knob was retained for the righthand change and that two ventilation outlets, complete with moving flaps, were provided. Then the canopy was thrust down upon us and near panic set-in. I did not even know how to start it, though the smell of diesel had inspired me to find the cockpit/engine fire button very quickly, in case it should be needed: it wasn’t operational anyway, as a colleague later proved!

Having pulled the stiff gearchange down into neutral, the left hand key could be pushed in to set the diesel ready for cranking over. As it was warm it fired with gratifying rapidity. It had not been necessary to remove the steering wheel to get me in, but even I had to put my knees high into the front hoop, to get my helmet to clear the perspex envelope that slipped rain droplets off without the need for a wiper.

I spent about 20 minutes rumbling the 2.4-litre around an enormous steering pad and came away impressed on a number of counts. First was the comfort of the ride, which must be quite something at high speed. The torsion bar front suspension and involved fabricated trailing arm with VW inserts for the conventional monotube dampers, plus the long wheelbase, allow a fine ride. There is an unwieldy feeling of wallow when turning, even at a modest 50 m.p.h. Get up on a banked track with the springs staggered on ride height for 200 m.p.h. plus and minimal ground clearance, and it must be a very different story!

Brakes, steering and gearchange all seemed pretty average, but that engine was a wonder. From 1,000 to 5,000 r.p.m. it does a good solid job, not with sensational kick in the back at this weight, carrying neccessarily tall gear ratios. The manner in which it will growl from 1,500 to 4,500 r.p.m. confirms that diesels can do a lot more than just puff heavily overladen lorries uphill in clouds of evil black smoke.

Necessarily “a brief encounter” but fascinating, nonetheless. — J.W.