Choosing an all-wheel-drive company car invariably means having to stomach higher fuel costs and emissions tax. Frustrating, especially when there might only be a handful of days a year when you actually need the extra traction.
Audi’s latest generation ‘Quattro with Ultra’ all-wheel drive system, due to be released later in 2016, claims to offer the best of both worlds by automatically switching between front- and all-wheel drive in fractions of a second. It only brings the rear wheels into play when absolutely necessary, sticking with front-drive in the majority of driving conditions to boost efficiency and cut fuel costs.
We tried the system on a pre-production Audi A4 test vehicle in Austria to find out more.
Why is it called Quattro with Ultra? Isn’t Ultra the name for Audi’s new diesel engines?
Kind of – Audi’s now applying the marketing label to any technology in its cars that boosts efficiency, including this new all-wheel-drive system.
How much fuel does it save?
According to Audi, its developers found the system used an average of 0.3 fewer litres for every 62 miles than a car with the ordinary Quattro system. It’ll still get through around 0.2 litres more fuel than a purely front-wheel-drive model, but the gap’s much smaller than before.
How does it feel to drive?
It’s genuinely all but impossible to feel when the system switches between two-wheel-drive and four-wheel-drive mode. Our drive included a mix of frosty mountain roads and motorways, and the system actually spent around 48 percent of the journey in four-wheel-drive mode, almost all of which was accounted for by the steeper, twistier sections.
How does the system work?
Via two clutches within the four-wheel drive system and some very sophisticated electronics. When switching to front-wheel-drive mode, the bigger of the two clutches, positioned at the rear of the gearbox and activated by an electric motor, disconnects the propshaft (which connects the engine to the rear wheels). Meanwhile the second clutch, a smaller unit at the rear axle, decouples part of the rear differential, reducing friction.
The system can reconnect the drive to the rear wheels and switch back to AWD mode in as little as 200 milliseconds, says Audi. Sensors monitoring everything from how hard the car is cornering to how much torque the engine is generating determine when to make the switch.
The Ultra system is unusual in that there is no centre differential, as you’d normally find in a four-wheel drive system.
When will the new system be released?
Mid-way through 2016, on the new Audi A4 Allroad. It’ll then gradually be rolled out across other large Audi models, including the next A5 and Q5.
The current Quattro system isn’t being replaced – the Ultra system will only be available with certain engines. The existing system will continue to be available alongside it, particularly on models with more powerful engines.
The Ultra system has been designed for Audi’s larger models, with their engines positioned lengthways – it won’t appear on smaller cars such as the A3 and TT, which mount their engines sideways.
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