Two cars at the antipodes, characterized by a common thread: they are compact cars at the peak of performance in their respective eras. The merit also goes to the four-wheel drive, this is how it has evolved in almost forty years
November 24th
Once upon a time there was the sports compact. Small on the outside and roomy on the inside, it was characterized by overall simple mechanics, but sufficient to guarantee performance and driving dynamics superior to those of an average small car, without worrying too much for cars of a higher category. However, over the years, the car industry has produced cars of this type that are ever more performing and mechanically advanced, such as to become similar in performance and status to sports cars. The first evolutionary passage of the hot hatch from “peppery” utilitarian to pure sports car is certainly marked by the introduction of four-wheel drive. Initially designed exclusively for off-road vehicles, from the 1980s the influence of racing and technological development also allowed its application on more compact models, with a purpose that was no longer merely practical, but with the desire to improve performance. The most significant example in this sense is given by the Lancia Delta HF Integrale. Created to replace the 037 in the world rally championship, it was not the first four-wheel drive car to win in this competition. In fact, it was preceded first by the famous Audi Quattro, then by the Peugeot 205 T16. However, the four-wheel drive Delta was also an extraordinary commercial success, driven by six world titles in the Constructors’ championship and four in the Drivers’ championship. In the nine years in which it was marketed, the Chivasso factory produced almost 45,000 units in various iterations: 4WD, Integrale 8 valves, then 16 valves, followed by the Evoluzione and Evoluzione II, with the related (and numerous) special editions, now coveted by collectors.
More and more SUVs
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A great transformation of the hot hatch genre that we have witnessed in more recent times is due to the overcoming of a great taboo, namely that an SUV cannot be fun to drive. The teaching imparted by the Porsche Cayenne meant that more and more manufacturers shifted their engineering efforts to the development of sporty cars, even in the lower segments, until they joined or even supplanted the sports compacts. The Cupra Formentor VZ5 is the perfect example of this phenomenon. It is in fact built on the same platform as the Leon sedan, but unlike it, it houses the most powerful and advanced engine available on the Volkswagen group’s compact cars. The Formentor VZ5 therefore borrows from the Audi RS3 the 2.5-liter in-line five-cylinder (here with 390 horsepower), but above all the most recent four-wheel drive system, which the Ingolstadt technicians call the “Torque Splitter” to distinguish it from the other “four”. Also in this case, four-wheel drive played a decisive role in differentiating a fast SUV, such as the 310 horsepower Formentor VZ 4Drive, from a full-fledged sports SUV.
Sporty design
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Considering the dimensions of modern cars, the Delta is small: only 390 centimeters in length, slightly less than today’s Toyota Yaris. Yet with a play on proportions, the height of only 137 centimeters and the width of 177 centimeters make it very aggressive and menacing. The Delta Integrale Evo 1 in fact flexes its muscles with its enlarged side wheel arches, which earned it the nickname “Deltona” to distinguish it from the 8V and 16V that preceded it. Our specimen also mounts 17″ approved rims which make it seem even more attached to the ground. With its 447 cm in length, 185 in width and only 151 cm in height, the Formentor VZ5 is characterized by a sleek and dynamic body, more both crosswagon and SUV. This stylistic approach gives it a markedly sporty character, which in this Taiga Gray limited edition is further accentuated by the carbon inserts of the rear extractor and the four copper-colored exhausts. In both cases, the outfit makes the monaco: the Delta Integrale and the Cupra Formentor VZ5 offer performance and driving dynamics worthy of sporty cars by definition.The merit is not exclusively due to the high power, but above all to the way in which it is discharged to the ground.
Delta Integrale: the viscous coupling
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Four-wheel drive on the Lancia Delta was introduced for the first time with the 1986 restyling and in particular with the arrival of the HF 4WD variant, powered by the 2-litre turbocharged 165 horsepower Thema turbo ie. Immediately used in the world rally, it was already updated the following year with the introduction of the Integrale, which however maintained an almost unchanged scheme, in which the protagonist was an epicyclic central differential with a Ferguson-type viscous coupling. It was an avant-garde solution, since this type of differential was considered very complex in those years. It is activated by blocking the blades which, following rubbing, generate an increase in temperature and a reaction of the silicone-based fluid in which they are immersed, whose viscosity increases with heat. In this way the differential locks, transferring more torque to the rear axle, with a distribution that on the first versions of the Integrale was 56% at the front and 44% at the rear, but which became 47%-53% for the 16-valve on. The torque at the rear is then further distributed via a Torsen differential, which allows the two wheels to vary their relative speed in an opposite and symmetrical manner, preventing the wheel that loses grip from spinning and sending torque only to the wheel with grip. Finally, the Delta has a free differential in the front end. This system, accompanied by an engine which in the Evoluzione we tested delivered 205 horsepower, made the Delta particularly effective in tight mixed terrain and easily adaptable to slippery surfaces, contributing to the numerous successes in the World Rally Championship. And, despite the age of the project, the road version remains a point of reference for limitless fun, assuming one knows how to make the most of its potential. In fact, if you want to drive it the Miki Biasion way, you need to know precisely the turbo lag times and predict the torque transfers of the central joint. But given the importance of this model, a guide that is not too exaggerated is enough to experience strong emotions.
Formentor VZ5: the Torque Splitter
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If the Delta represents the completely mechanical approach to four-wheel drive, the Cupra Formentor VZ5 is the perfect demonstration of how in the distribution of torque between the axles, the mechanical component has been accompanied by sophisticated electronic systems, which have assumed an increasingly predominant role . The VZ5 features the latest all-wheel drive system available on Volkswagen Group compacts, on a par with the VW Golf R and Audi RS3. The previous versions of the German super-compacts exploited a Haldex-type central joint, which through an electronically controlled clutch allowed the car to move using only the front axle, to then distribute the torque also on the rear axle when it was lack of adherence. In the wake of what was introduced by Gkn with the Twinster, applied on the Ford Focus RS, the Vag group has adopted a permanent four-wheel drive system which allows the rear axle to always receive torque from the transmission shaft, and then distribute the torque between the individual rear wheels – up to 100% on a single wheel – via two multi-plate clutch packs. With this new system, developed by the giant Magna, the Formentor VZ5 travels under normal conditions with a 50:50 torque split, but this can vary depending on the grip conditions or corner angle. In order to establish which axle or wheel needs more torque, the VZ5 relies on a series of control units placed in key points. So wheels, brakes, steering and rear differential communicate constantly with each other to ensure the car neutral or oversteering behavior depending on the selected mode. This is why the Formentor VZ5 has the ability to be safe and predictable even when going fast, but at the same time to be a fanciful drift toy, when conditions permit.
The future is simplified
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Despite the effectiveness and refinement achieved by current systems, which manage to transfer torque between the axles instantaneously, this technology is destined to disappear. In fact, with the growing electrification, engineering efforts have increasingly shifted to the development of hybrid four-wheel drive, with an axle managed by the internal combustion engine and an independent axle. The latest evolution of this system is the Gkn eTwinsterX, designed for the rear axle of plug-in cars, which simulates electric torque vectoring. And yet, given the halt to sales of cars powered by a heat engine from 2035, we will hardly see its application on mass-produced cars. Rather, the exclusively electric propulsion will lead to a simplification of the mechanics, offering the possibility of installing electric motors on the individual axle shafts and managing their power through sensors and control units. This solution is already applied to hybrid cars such as the Honda Nsx, and obviously also finds space in electric cars such as the new Maserati GranTurismo Folgore, which has three electric motors, two of which are located on the rear axle shafts. We just have to wait to test it to get a taste of the future of the sports car.
November 24, 2022 – 09:04
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