Audi quattro all-wheel drive explained
We explain everything you need to know about the Audi quattro all-wheel drive system
Audi quattro all-wheel drive, quattro four-wheel drive or quattro 4x4; whatever you want to call it, there’s no doubt the trademark Audi ‘quattro’ brand name is etched into drivers’ consciousness here in the UK and all around the globe.
The name first sprung to prominence with the Audi Quattro rally cars which used 4x4 to great effect in the sport’s golden era in the 1980s. Since then the term quattro (note - without the capital Q) has been applied to various types of all-wheel drive set-ups used on Audi passenger cars.
In Germany around half of the cars Audi sells have Quattro all-wheel drive fitted, and it’s very popular here in the UK too. The quattro option can be specified on virtually any model line in the Audi range. So when you’re browsing the ‘quattro for sale’ adverts you'll find plenty of quattro equipped models including the A3, A4 and A5 to tempt you. The quattro drivetrain is also fitted as standard to all the Audi brand’s high performance machines; there’s no doubt the influence of the original ‘Quattro’ rally car still resonates with buyers of quattro RS models, adding to their appeal.
So what does quattro do?
We know quattro signifies four-wheel drive – indeed quattro means ‘four’ in Italian’ – but why is this a good thing in the first place? Ask an automotive engineer, and you’ll get a very complicated set of answers, but for our purposes it’s enough to imagine the forces working on your car’s tyres as they grip the tarmac.
In a ‘normal’ two-wheel drive car, all the power is put through the front or rear wheels – depending on whether it’s front- or rear-wheel-drive – whereas all-wheel drive or quattro means the work is shared by all four tyres. As a result, whether you’re accelerating or cornering, the tyres of a quattro spec Audi will provide a greater level of grip than a two-wheel drive model.
This has obvious safety implications if you enter a corner or wet roundabout a little faster than is advisable, as you have a greater margin for error before the tyres lose grip and skid off the road. It’s not just roundabouts either, as many Audi buyers choose quattro if they live in the countryside where roads are often muddy, or in remote or higher altitude parts of the country where snow and icy conditions are more common.
The same principle of maximising traction applies to quattro performance models that are capable of faster acceleration and cornering thanks to the additional grip from having four driven wheels.
We should also mention quattro SUVs and off-roaders, as Audi also offers quattro Q3, quattro Q5 and quattro Q7 models. Again the advantage is extra grip, essential for anyone venturing off-road onto mud or gravel trails, and quattro also comes into its own when towing as you’re less likely to lose traction.
How does the Audi quattro system work?
There are three basic types of quattro set-up, and they have slightly different characteristics, although you have to be quite an experienced driver to notice a difference in practice.
The system fitted the A4, A6 and Q8 is most common, and here the quattro system has a default engine power split that’s biased 60% to the rear wheels and 40% to the front wheels. It’s designed to give the driving feel of a rear-wheel drive car in normal use, but if the rear-wheels begin to lose traction the system can instantaneously divert more power to the front wheels.
Smaller models such as the quattro A3 and the TT quattro which shares the compact hatchbacks engineering platform have a set-up that reverses the bias. Here the quattro system powers the front wheels almost exclusively until they start to lose grip, at which point a multi-plate clutch diverts power to the rear wheels – but they never get more than 50% of it.
The Audi R8 quattro boasts supercar performance, and it’s quattro system sends 85% of engine power to the rear wheels in normal driving, again diverting power instantly to the front wheels to prevent traction being lost at the rear.
Is quattro worth having?
The price differential between quattro all-wheel drive and rear-drive models is significant but not excessive, and if you’re considering it on a new Audi purchase, don’t forget you’ll likely benefit from a higher residual value when you sell the car on – used quattro models are in demand too with prices remaining strong for older cars.
Whether you really need it or not, depends on your style of driving and the types of road conditions you’re faced with. It must be said that the majority of Audis without quattro don’t end up crashed on wet roundabouts, after all.
It’s also worth remembering that tyre condition and specification is potentially a more significant factor when it comes to grip and traction, and choosing to invest in a set of winter tyres for snowy and icy conditions may bring greater benefits than quattro alone.
The downside of extra cost, and a marginal fuel consumption increase due to extra weight must also be balanced against the benefits.