All roads lead to Audi

Dy­namic, fast and fru­gal, Audi’s new A4 All­road Qu­at­tro of­fers a so­phis­ti­cated ‘ul­tra’ sys­tem that pre­dicts when all-wheel-drive is needed, re­ports Charles Ran­ge­ley-wil­son

Country Life Every Week - - In The Driving Seat Audi A4 Allroad 2.0 Tfsi Quatt -

AN un­for­tu­nate side ef­fect of the lan­guage bar­rier and the in­ten­sity of the tech­ni­cal tsunami my Audi en­gi­neer was attempting to ren­der into English was that I was giv­ing a good im­pres­sion of be­ing an id­iot, in­ca­pable of un­der­stand­ing even the most ba­sic ideas be­hind the work­ings of a mo­tor car. Thus, I was re­lieved when, in the wettest in­ter­lude of the Bavar­ian rain­storm Audi had laid on to il­lus­trate the ef­fi­cacy of its new ‘Qu­at­tro mit ul­tra tech­nolo­gie’, I thought of an anal­ogy our Audi guru had never heard of.

I was try­ing to get my head around what the ‘ul­tra’ bit did on this new A4 All­road, when the light­bulb came on. ‘It’s like dou­ble de-clutch­ing,’ I ex­claimed tri­umphantly. Now, it was his turn to look baf­fled. ‘It’s how you change down gear in vin­tage cars,’ I ex­plained, try­ing not to look smug. ‘You have to spin up the gearbox to stop it grind­ing, so you let out the clutch as you go through neu­tral and give the throt­tle a blip.’

I was al­ways go­ing to like this car, largely be­cause I drive the older model and I’d say she’s sec­ond favourite only to my long-missed

This 4WD of­fers real sav­ings on the drinks bill

Peu­geot 205 GTI. This new ver­sion was like mine, only more so—dy­namic, but not fre­netic; re­fined, but not boule­vard; fast, but not in­sane; fru­gal, but not sanc­ti­mo­nious.

Yes, there’s sharper steer­ing in a BMW, more room in a Volk­swa­gen and the A4 ver­sion of the All­road is re­ally a ma­cho A4 in heel­rais­ers. How­ever, if you want all­wheel drive (AWD) be­cause you live where the roads are of­ten cov­ered in turnips and you go down rough tracks as of­ten as you drive to Lon­don, the A4 All­road is a great car.

Now, back to the tech­ni­cal be­fud­dle­ment, be­cause the re­ally in­ter­est­ing thing about the new model is un­der the floor­pan and, to see why, we must waltz through the pros and cons of four-wheel drive (4WD).

Most peo­ple who have ever put fuel in one will know that a big draw­back of cars with per­ma­nent AWD is how much they like their drink. It’s thirsty work run­ning those two ex­tra wheels and their drive shafts, pin­ions and wid­gets. You might have trac­tion when you need it, but you also have a hole in your wal­let each time you nip to the fuel pump.

That’s why ‘soft-road­ers’ (such as Volvo’s XC se­ries and Range Rover’s Evoque) have a special clutch be­hind the gearbox that feeds power to the rear wheels only when the front wheels start to slip, which gives bet­ter fuel con­sump­tion, even if the re­ac­tive sys­tem isn’t ex­actly pure 4WD. Plus, the drive shafts and pin­ions of the rear wheels turn even when they’re not en­gaged—and all that fric­tion still im­pacts on fuel econ­omy.

Audi’s at­tempt at the 4WD holy grail—in­stant, pre­dic­tive 4WD trac­tion, but closer to 2WD econ­omy —lies in a sys­tem akin to dou­ble de-clutch­ing, in which, most of the time, only two wheels are driven. When power is needed at the rear, a clutch spins up the drive shaft and a sec­ond snaps two castel­lated wheels to­gether in the rear dif­fer­en­tial. It’s very clever and hap­pens in a max­i­mum 250 mil­lisec­onds. Vi­tally, the sys­tem doesn’t wait for the front wheels to slip be­fore en­gag­ing.

As my Audi en­gi­neer boasted, I wouldn’t be able to spin the wheels, even if I stamped on the throt­tle in a pud­dle, be­cause a smor­gas­bord of com­put­ers mon­i­tors ev­ery­thing about the car and the way it’s driven to ‘pre­dict’ when AWD is needed.

Usu­ally, I’d re­serve a dis­sec­tion of dif­fer­en­tial in­ter­nals for the mid­night slot on Ra­dio GreaseMon­key, but ‘mit ul­tra’ is worth the oily di­ver­sion. It ap­pears to of­fer the best of both worlds— a 4WD sys­tem that’s ef­fec­tively ‘per­ma­nent’, that is pre­dic­tive, not re­ac­tive, and which of­fers real sav­ings on the drinks bill. Perfect! Make mine a dou­ble.

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