Talk Morgan Forums Community Vehicle Talk (non-Morgan) Jaguar XE AWD

I thought the ancient Britains fled to Wales covered in woad.

Cue photo of Bodicea indicating left and turning right.....

Wales covered in woad? Now that would be a sight to see

And that wasn't a fishy pun

Is it labelled "AWD" because people can't count to four these days? Or is the term "4WD" just too old-fashioned for the advertising dept.?

Technically, they are slightly different things:

All-Wheel Drive (AWD): A drivetrain that employs a front, rear and center differential to provide power to all four wheels of a vehicle.

Four-Wheel Drive (4WD): A drivetrain that employs two differentials and a transfer case to provide power to all four wheels of a vehicle.


For example, my Wife's Jeep Wrangler is 4WD because she has to choose to engage the transfer box, whereas my GLA is AWD because the centre diff apportions the torque continuously between all four driven wheels. Confusingly, the GLA is labelled 4-matic, go figure....

Morgan could introduce an AWD M3W but not a 4WD M3W, we need to keep an open mind around this.

Neither of which are wholly applicable to the majority of Land Rovers (ignoring the Freelander and later Defender/RR/Disco) out there...

A rather interesting destinction. To my mind there are several systems.

The conventional old fashioned 4WD uses a transfer box that will send 50% of the power to the front wheels when inserted but is not suitable for on road use because it does not have a differential between front and rear axles. These systems usually have front wheel hub locks so that the front differential etc. Is not rotating when not in use. In this system provided both wheels of at least one axle have grip the vehicle will move. I have had the experience of being blocked when the left front and the right rear wheel were off the ground. Most 4WD vehicles would also have a low range gearbox which would allow the vehicle to move at crawling pace if necessary.

A more sophisticated version allows on road use when 4WD is engaged because it has a centre diff. Unless this centre diff has some limited slip arrangement the vehicle would be blocked if only one wheel completely loses traction. I would say that most modern 4WD vehicles would have some such system.

An AWD (or constant 4WD) was developed to give better traction in all conditions and came to fame for its use in rally cars, the Lancia Delta Integrale for example and later the Subaru WRX. To be effective these systems need some sort of limited slip arrangement in the differential between the front and rear axles and ideally both the front and rear axles should have limited slip differentials. Provided nothing is slipping these vehicles would have 25% of the power going to each wheel. The downside is that they have high consumption of fuel and tyres. The little AWD Subaru Justy that Alis has just replaced with a Polo had attrocious fuel economy. There are more sophisticated systems that apportion a different percentage of power to the front and rear wheels in normal use but this can change if the wheels of one axle start to slip.

The more modern AWD systems use computerised traction control on all wheels and will drive only the rear wheels until some slip is detected at that point power is transfered to the other wheels. This has now been developed to the point that vehicles equipped with these systems and winter tyres can perform surprisingly well on snow but maintain excellent fuel economy on dry roads.

Don't forget many in your second paragraph have a lockable centre diff Peter, giving you the same as the part time 4WD in your first paragraph when in 4WD.

Good point Graham. I had overlooked that.

For those that have Facebook there is a video of a Jaguar F-Pace on the ski run at Bormeo. I have seen another video of an SE AWD with winter tyres doing the same thing on the same day.

https://www.facebook.com/gruppoclericiautoJaguarLandRover/videos/1241536825900903/

If you don't have an account you can still watch the video if you click on "Not now" or whatever it is in the pop-up. this reduces the size of the pop-up and then by clicking on the video you can select full screen mode.