The ‘quattro’ name has been used by Audi since 1980 and applies to the all-wheel-drive system fitted to the German brand’s road and racing cars. The system itself is spelt with a lower case ‘q’ after the Italian word for ‘four’ – Quattro with a capital ‘Q’ applies to the iconic rally car from the ’80s.
What is Audi quattro?
The quattro moniker has been synonymous with Audi since 1980 when it first appeared on their revolutionary – and hugely successful – rally car of the same name. It refers to the all-wheel-drive system employed to devastating effect at a time when the rallying competition used two-wheel drive.
Not only did it help Audi win two world rally championships on the trot but it filtered down into the company’s road cars. You’ll most commonly find quattro fitted to Audi’s high-performance RS models including the RS3, TT RS and the mid-engine R8 super car.
How does quattro work?
Most all-wheel-drive cars come fitted with a device called a transfer box. It sits after the gearbox and splits the engine’s power between the front and rear axle. Unfortunately, these systems are often heavy and difficult to package in small cars.
Audi’s engineers instead developed a centre differential – a set of rotating gears with two output shafts – to direct the engine’s turning force – called torque – to both the front and rear wheels. Not only is this system compact enough to be fitted within the car’s gearbox, but it can be infinitely adjusted to send power to whichever wheel has the most grip. As a result, it’s also known as a Torque-Sensing, or ‘Torsen’, system.
These units are smaller and lighter than a conventional transfer box and they’re more efficient, too. They obviously provide extra grip when travelling on extremely slippery surfaces but are useful all year round by enhancing the car’s roadholding ability even in the dry.
Are there any disadvantages to quattro?
In quattro systems, the need to package all the components means the gearbox is longer than a conventional two-wheel drive unit. This forces the engine to be positioned further forward in the car. All this extra weight over the nose can lead the front wheels to lose grip during exceptionally hard cornering, commonly known as understeer. That said, this will only really be noticeable on a race track.
Cars fitted with permanent all-wheel drive – such as Torsen quattro systems – are often less economical than conventional two-wheel drive cars, too. This is because some of the engine’s power is wasted driving the extra gears required to turn all four wheels.
How does it work for smaller Audis?
Some more compact Audis, including the A3 and TT, employ a different quattro system, featuring a device called a Haldex unit. In contrast to a Torsen system, they send nearly all of the engine’s torque to the front wheels in normal conditions. If they detect a wheel slipping, however, a secondary clutch can kick in to divert as much as 100 per cent of the torque to the rear wheels.
This difference between Haldex and Torsen systems means some die-hard Audi fans will often refer to cars equipped with the Torsen system as ‘true quattros’. Unless you regularly push your car to its limit, however, you probably won’t notice any great difference between how these cars feel to drive.
Is the R8 different to other quattro models?
Unlike any other Audi, the R8 is mid-engined – its 5.2-litre V10 is mounted behind the driver and ahead of the rear wheels. As a result, there’s no space for a gearbox or differential in front of the rear axle. Instead, both are mounted behind the back wheels and a second driveshaft is used to send power to the fronts.
The R8’s mid-engined layout grants it a more even weight distribution than other front-engined Audis meaning its quattro system can send more torque to the rear wheels without the risk of losing traction. This helps it feel more agile and sporty than a conventional all-wheel drive car. Typically 85 per cent of the engine’s 547hp is sent to the rear wheels with only 15 per cent making its way to the front.
What is Audi quattro with ultra technology?
The latest development of the company’s famous all-wheel-drive system is all about saving fuel and cutting CO2 emissions. Audi claims its ‘ultra’ technology could boost an Audi A4 3.0-litre diesel’s fuel efficiency from 60.1mpg to around 64mpg.
It works by allowing the engine to drive just the front wheels most of the time. When the extra grip from all-wheel drive is needed, power is sent to the rear wheels via two clutches – one mounted to the car’s gearbox, the other to the rear axle.
Not only will it help improve fuel economy but it’ll help reduce unnecessary wear and tear on the engine and gearbox. The system can also react quickly to changing conditions and shift the engine’s torque between all four wheels to keep you pointing in a straight line.
What about the future?
The R18 e-tron quattro Le Mans Prototype, shown above, made use of a traditional diesel engine to drive the rear wheels, while an electrical system – charged by energy recovered under braking – powered the fronts.
The A3 e-tron already uses a system similar in principal to the R18’s and this technology could be rolled out to the rest of the Audi range in due course. The instant torque from an electric motor can be deployed much more efficiently than from a regular combustion engine and should help future Audi models react to changing conditions even faster.
Sounds gripping. Now I want to look at some Audis…
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