ajb723

Trying to decide between MB C300 and A4. Is there any significant difference in performance in snow between the 4wheel drive formats?

yareally

4matic isn't full time AWD on the C class I believe.

Eric5273

In the snow I doubt there would be much difference. But in dry weather, Quattro will have things like torque vectoring which will give the A4 better handling than the C300.

Glisse

I agree with Eric.

In snow, being on the right tyres will make more difference than those between the AWD systems.

Whilst Audi are available in FWD versions, the basic engineering of the platform is done on the basis of quattro/AWD. In the case of Mercedes, and BMW, AWD is tacked on after the event.

In alpine Europe, Audi is the market leader in this class.

shansoft

A4 does not have torque vectoring. It's S4 with optional sports differential.

Eric5273

Here is the 2017 A4 brochure. Look at page 9...

https://www.audiusa.com/content/dam/...rX_lowres2.pdf

"....available quattro all-wheel drive featuring electronic torque vectoring for enhanced agility...."

superswiss

The A4 has torque vectoring by braking. It slightly applies the brakes to the inner front and rear wheels to send more torque to the outer wheels while cornering. The sport differential on S and RS models is active torque vectoring on only the rear axle. Both of these systems can also be combined. The first model that combined them was the RS5. Torque vectoring by braking became possible with the new self-locking center differentials. The old torsen differential didn't allow it. After the RS5, the B8.5 S4/5 S-tronic also combined the sport differential with torque vectoring by braking. The B8.5 S4/5 6MT did not, because they still have the old torsen center differential. At this point, other than the S4/5 6MT, all current and new longitudinal platform models have the self-locking center differential with torque vectoring by braking and in addition if available the sport differential adds active torque vectoring to the rear axle.

EDIT: One correction, the all-new Allroad doesn't have the self-locking center differential as it is the first model to use the new Quattro Ultra, but it has torque vectoring by braking and Quattro Ultra can be combined with the sport differential, but that's currently not an option on the Allroad.

EDIT2: BTW, the self-locking center differential is torque vectoring front to rear. By controlling how much braking force is applied to the front inner wheel vs the rear inner wheel the car's electronics can control how much torque is sent front to rear when cornering.

audi8k

Hi Superwiss, do you have the information abput Crown Gear vs Torsen diff from a reliable source? The blog linked below states that the B9 quattro (which to my knowledge is only available with S-tronic) use Torsen and not Crown Gear.

Quote: "There is another major change for the B9 A4: it looks like Audi has given up its crown-gear center differential, therefore on the 2016 A4 with Quattro AWD system, it is using the Torsen C differential (please note: Audi has a long tradition of using the Torsen differentials in its vehicles previously; the crown-gear type is the firm’s attempt to design/build a different central differential than buying it from JTEKT Torsen, a company now owned by Toyota) ."

All-New 2016 Audi A4 Announced - YouWheel.com - Car News and Review

Glisse

Too much is being made of the self-locking centre gearing set being used in various MLB quattro models. The crown gear version is slightly shorter and slightly lighter than the planetary geared set - all the other components are the same. A crown gear set "grips" slightly more quickly than a planetary set. But it is also more abrupt between releasing and engaging. Fine with lower torque NA engines, less ideal in high torque FI engines. Which is now most of them.

The crown gear set was used in several models following the RS5. But Audi do not specify what type of gear set is being used in various models. You need to crawl underneath to measure housing length, or obtain a parts list. But why bother - my S5 has a planetary gear set, and my A7 has a crown gear set. But I could never pick that up from actually driving them

The centre differential gear set is just one part of the entire system. So "Torsen and not Crown Gear" is making a mountain out of a molehill.

The quoted article is wrong. The change from a Torsen sourced to an Audi design first appeared in 2005 on the RS4. The crown gear differential "option" came later, in 2010. Whether this enabled Audi to avoid paying, or reducing, patent license fees, IDK.

This shift from Torsen supplied to in-house design was 2 years after a Toyota subsidiary had bought Torsen from Robert Bosch (still a major Audi supplier) in 2003.

But JTEKT is "just" an automotive supplier like many others. Their primary business is power steering systems. These operations are best thought of as very advanced machine shops.

See various info here, if interested:

TORSEN

JTEKT Brazil LTDA
I've used the Brazilian office of JTEKT, because it amuses me that it is located at 1200 Avenue Volkswagen Audi

Self-locking center differential ? Audi Technology Portal

Crown gear differential ? Audi Technology Portal

Drivetrain ? Audi Technology Portal for history

superswiss

Not unless you speak German. My source is Audi Germany. It's even stated on audi.de that the B9 A4 uses the planetary gear self-locking center differential.

Just a comment on Glisse's post. No current S5 uses the planetary gear set self-locking center differential. The 6MT S5 has the old torsen center diff and the B8.5 S-tronic S5 has the crown-gear self-locking diff. In my experience there is a major difference in driving dynamics between the old torsen and the new self-locking diffs with torque-vectoring, so I don't agree with your assessment. I would never go back to a Quattro with the old torsen diff.

Here's more info on the planetary-gear self-locking center differential. This is not the torsen diff. The torsen works on a different principal.

Self-locking center differential ? Audi Technology Portal

EDIT: Didn't have the link handy anymore. If you do speak German, here's all the info about the A4's powertrain directly from the Audi Germany website. I trust this much more than some blogger that probably mistranslated German information into English.

Motoren und Antrieb > A4 Limousine > A4 > Audi Deutschland