tron786

So I tried getting info on 4Matic in its current functionality but the info on the web is old.

My SA said that the 4Matic now is not permanent AWD and that the car is mostly driving as a RWD until there is loss of traction and then the AWD kicks in. This could happen on or off road.

Please advise

Inomis

From MB USA website:

4MATIC all-wheel drive
Standard
In any season, on any road, 4MATIC® all-wheel drive adds to your confidence and control. Always engaged and optimizing torque to every wheel, 4MATIC integrates with ESP®, our standard Electronic Stability Program, for maximum effectiveness in corners and slippery conditions. It also incorporates our 4-wheel Electronic Traction System (4-ETS®), which monitors for the first sign of wheel slip and responds to ensure torque is sent to the wheels with the best grip, even if that's only one wheel. (Disclaimer)

Mickfx

and more from MB:

Under normal conditions, the compact, lightweight system channels the engine's torque to the front and rear wheels through a center differential, for sporty balance and agile handling. When traction demands change, 4MATIC reacts instantly and expertly to maximize control. By sending power to the wheels that can use it best, it helps you feel a rewarding sense of confidence in any season.

Penn

The 4matic are permanent all wheel drive but the torque split varies dependant on the particular model, for example the 250 diesel has as 69% rear 31% front torque split while the petrol and 220 diesel run a 50% Front 50% rear torque split.

Donnnn

I as told on the GLC is was normally 55% rear

tron786

So it's rear biased.
But at cruising speed on a flat hi way road with good traction will the ratio change to more than 55%?

Donnnn

The only doubt I have that the ratio is normally 55/45 is your SA's statement. But his response makes me curious too.

Perhaps they unlink the front at highway speeds for better mileage.

Inomis

If the front wheels were not engaged, it could not sense if they have any traction. So then if the rear lost traction it would it not know where to send the torque.

Believe the website, "always engaged".

Donnnn

I assume the car has four wheel speed sensors for the ABS

fabbrisd1

Let me try to clarify - for US GLC 4matic models - yes - the torque distribution is 45/55 front-rear - and YES it is "all-time-all-wheel-drive" 4matic - using the 9G transmission - using a multi-clutch center differential vrs the transfer case used in 7G/7G+ 4matics.

That 9G 45/55 split for 4matic/All-Wheel-Drive in other models - such as the GLE450 Coupe - is sometimes termed "Sport All Wheel Drive".

My personal impression - a bit more torque to the rear gives a more "impressive feel" under firm acceleration.

I would "guess" where the confusion came in - Mercedes also call the "on-deman-all-wheel-drive" for the GLA/CLA models "4matic" - however on this FWD platform - the rear traction is kicked in "on demand" - similar to several of the Japanese "AWD" systems.

Hope this helps - keep the beat !

tron786

This clears it up. Essentially the 4matic in the SUV cars are permanent AWD unlike the 4Matic in the sedans/ non-SUV are AWD-on demand

fabbrisd1

For Mercedes - in the US only the CLA Sport Coupe/4matic and GLA SUV/4matic are both FWD with AWD "on demand" - all other Mercedes/4matic models are All-Time-AWD