LIKE the idea of running an all-wheel drive car on the business, but think that the penalty in fuel efficiency and higher CO2 isn’t worth the extra for more grip?

Well listen up, as Audi, one of the pioneers of production four-wheel drive cars, has come up with what it thinks is the solution, that works with its greenest Ultra models.

However all the powerful performance models, with over 500Nm of torque, will continue with the regular Quattro set up.

Called Quattro with Ultra technology and debuting in the A4 Allroad which goes on sale this spring, with this version of Quattro all-wheel drive it actually starts in two-wheel drive – thus removing the need for that extra fuel to power the extra pair of wheels.

That sounds clever you’re thinking and it is – but how does it work? Well instead of one clutch, this new Quattro drive uses two. One where you’d expect it be between the gearbox and central propshaft, but there’s also another on the back axle that, via numerous sensors, will determine whether two-or four-wheel is needed.

These sensors monitor everything from your steering input to how much grip the tyres have, plus the outside temperature. This happens 100 times a second, where the car decides if four-wheel drive is necessary, making a final decision just half a second before a slide occurs.

With all these sensors, you’re probably thinking this Quattro system is going to be heavier than standard – well you’re wrong, as according to those clever chaps at Ingolstadt, it’s actually 4kg lighter, because some parts, such as the propshaft, aren’t built for use all the time.

This Quattro system also works with the car’s stability control sensors to determine what type of driver you are. Dynamic driver? Well, then this system might think that you need four-wheel drive more than normal.

You’re sold, right? But, show me the figures? Sadly Audi couldn’t give us exact figures, but their engineers reckoned there was an improvement of 0.3l/100km during German testing.

So what’s it like? Well, we headed to Austria for a drive in one of the latest 248bhp, 2.0-litre petrol A4s fitted with the new Quattro system. Then as a reference, we had the chance to try another A4 with the standard Quattro system.

The first car, fitted with the prototype Quattro with Ultra technology also had a data logger, which via an iPad was able to tell when four-wheel drive was activated over the 45-mile test route.

A debrief after the drive showed that the prototype on cold but dry Austrian roads still activated the four-wheel drive 60% of the time. However the biggest gains are likely to be where four-wheel drive is needed least – such as dry motorway work.

Most impressive is after driving these A4s back to back, we couldn’t tell any differences in the way the Quattro systems feel when you drive – even with the new one switching between two and four-wheel drive.

After the A4 Allroad, the next model to get this system will be the all-new Q5 due later this year, with the rest of the A4 range expected to receive this clever four-wheel drive tech in 2017.