Car and Driver: Quattro Ultra: Audi’s New, More Efficient AWD System

[FeedBot]

-

Audi is rolling out a new version of its Quattro all-wheel-drive system that promises an efficiency improvement of at least 5 percent—more on the highway. Available exclusively on the VW Group’s modular-longitudinal platform, the new system, which Audi calls Quattro Ultra, decouples the rear axle when it’s not needed. Fewer moving parts equals less friction.

-

-

 

-

-

This is a particularly big deal for Audi, since a whopping 43 percent of all Audis globally are all-wheel drive. Audi’s new Quattro Ultra will launch first on the new A4-based Allroad, slated to go on sale in the summer of 2016.

-

-

This is how it the system works: When the software decides that front-wheel drive is sufficient, it electromechanically disengages a multi-plate clutch positioned right behind the transmission. A clutch in the rear differential also decouples to stop the prop shaft from rotating in order to reduce friction and losses. The reverse process, engaging the rear axle, takes a maximum of 250 milliseconds.

-

But as quickly as it works, Audi doesn’t want the system to merely react to road conditions; in fact, reactive engagement is only the last resort and seldom happens. One instance would be when the car is traveling on a dry road and suddenly hits a slippery spot. In most circumstances, all-wheel drive already will be pre-engaged because of the proactive and predictive decisions. For example, the car will know when to expect adhesion loss at a given cornering speed about 0.5 second in advance. In the future, navigation data and car-to-car communication will further reduce the need to react.

-

On the predictive level, there are many parameters, measured every 10 milliseconds. Audi will engage the rear axle when the stability-control system is in Sport mode or when it’s turned off, when stability control engages, at high engine speeds, during kickdown or strong gas-pedal inputs, and during spirited cornering. The threshold for all-wheel-drive engagement is generally lower when the car detects a “dynamic” driver. And it is thoughtful enough to recognize your desire to go drifting; the system is happy to help out and transfer the bulk of torque to the rear wheels when the driver wants to steer the car with the rear axle. If needed, all-wheel drive can engage up to top speed—a capability that some competitors don’t have.

-

Audi’s goal is to make models equipped with the Quattro Ultra system feel exactly like a car with full-time all-wheel drive. During our test drive up the old Brenner Pass in Austria, with an Audi engineer riding along with a laptop programmed to show us when all-wheel drive was active and when it was not, it was impossible to detect the engagement or disengagement of the rear axle.

-

Quattro Ultra was developed together with supplier Magna, and it took Audi a whopping five years to get the system ready for production. It eventually will launch in almost all MLB-based models with four-cylinder engines and some lower-powered six-cylinder models. Expect to see it on the A4, as well as the next-generation A5, Q5, A6, and A7. It’s currently not able to handle the torque of the high-performance models, and it probably won’t be fitted to those cars. Quattro Ultra also is not compatible with Audi’s rear sports differential.

-

---

-

• -
• 2017 Audi A4 Allroad Quattro: The Only Way We Get an A4 Avant-
• Audi Switches Focus to eTron, Delays Other Models-
• Audi Brand Research: Tests, Reviews, Specs, Pricing, and More-

-

---

-

Available both on models with the manual transmission and with the dual-clutch automatic, Quattro Ultra carries no penalty. There will be no price premium, and it’s almost 10 pounds lighter than the old Torsen system. A similar system, developed by supplier GKN, is offered in the Range Rover Evoque, but it falls a bit short of the Audi’s comfort and predictive properties.

-

Read Full Article