[shivaswrath]

Originally Posted by drob23

The weight is substantially greater - S4 3935.3 (lb) - 335i xdrive 3582 (lb) -

This is key in the handling department...and the reason I wanted a RWD.

[drob23]

Originally Posted by shivaswrath

This is key in the handling department...and the reason I wanted a RWD.

I edited the values for curb weights for the various BMW 3 series models with AT, as they were somewhat wrong. Interesting how there's about a 300lb difference between a 328i 6MT and 335ix AT. The gulf between an S4 and 328i MT is huge and will definitely be MUCH different in terms of driving dynamics - especially in corners.

But the 335ix drive is only 200lbs lighter than the S4, and with the weight balance thrown off with the heavier engine/x drive equipment, I would think there won't be too big of a difference between them. I've actually read some complaints about xdrive understeer when exiting corners, since the xdrive will clutch power towards the front when applying heavy throttle at moderate speeds. The ZF rear torque vectoring on the S4 is the star in this situation, which is designed specifically to combat the understeer without applying brakes on the inner wheels.

The sensation of RWD vs AWD is what really distinguishes the two. The vehicle pitch due to RWD acceleration is awesome, you can't argue with how satisfying it is. The S4 feels more like a pull, and while it is probably overall harsher and faster, it doesn't cause you to lean back like the 3 series (but it definitely puts a smile on my face ).

[PierreTT]

I owned a 2011 S4, MT,
I now have a F30 335iX, MT

S4 was faster (stock vs stock)
335iX is more fun to drive (less understeer, more RWD bias)
335iX look&feel is a little better (interior, visibility, feel...)

Both great cars to me

Try them both and decide

[sean10mm]

Originally Posted by drob23

The electronic clutch pack that makes up the x-drive is really not a center differential - ie torque sensing - and thus only clutches power (max 50-50)

This part is incorrect. xDrive will send up to 100% to either axle.

http://www.bmw.com/com/en/insights/t...echnology.html

[335BBS]

Originally Posted by cardsdoc

I would have considered it more if the leasing wasn't so bad. Huge difference in monthly payments.

You get what you pay for.

[335BBS]

Originally Posted by rich1068

I 'aspired' to an Audi a few years ago. Got one with all the bells and whistles but unfortunately it was the dullest car I've ever had the displeasure to own. A VW in a posh frock.

Just like a Bugatti, Lambo , Turbo Porsche, R8........................

[drob23]

Originally Posted by sean10mm

This part is incorrect. xDrive will send up to 100% to either axle.

http://www.bmw.com/com/en/insights/t...echnology.html

I researched this quite a bit and found it to be erroneous marketing on BMW's part. It is not a differential but simply a clutch pack that can send torque to the front wheels - that is the rear axle is always affixed to the drivetrain and cannot be disengaged by xdrive.

I'll look for a good source on this, but seem to remember it from these forums, if I'm wrong I'll retract my statement - keep in mind marketing documents are not always accurate.

Edit - The most objective source I can find is here: http://www.awdwiki.com/en/xdrive/ Notice that it says torque can shift from 50-50 to 0-100. I'll look for the thread where some very informed BMW owners debunked the myth that xdrive can split torque 0-100 to 100-0.

[JohnVidale]

While I have little experience in interpreting transmissions, if the rear wheels are spinning frictionlessly on ice, how can they have any torque? Torque is a force applied, not a rotational velocity. No friction = no torque, at least in physics.

Perhaps the rear wheels remain engaged, and turning as fast as the front wheels, but at times they are applying no torque, and all the torque is coming from the front wheels?

[drob23]

Originally Posted by JohnVidale

While I have little experience in interpreting transmissions, if the rear wheels are spinning frictionlessly on ice, how can they have any torque? Torque is a force applied, not a rotational velocity. No friction = no torque, at least in physics.

Perhaps the rear wheels remain engaged, and turning as fast as the front wheels, but at times they are applying no torque, and all the torque is coming from the front wheels?

Yes, this confusion is easy to see. You never want to the wheels to slip because this lowers the coefficient of friction (sliding vs non-sliding) and thus makes a loss of traction situation even worse. Not to mention, if the wheel is spinning uncontrollably at high speed, I imagine if it hits a patch of road with high friction it could apply a very strong yaw moment and cause you to lose control. I'm no expert on vehicle dynamics, but this is my intuition.

In the scenario you present, assume the front wheels have good traction while the rear wheels are on ice (somewhat academic example I suppose). In this case, you do not want any torque to be transferred to the rear wheels. Ideally, the center differential would route all torque to the front wheels and the rear wheels would roll without slippage. In the case of xdrive, this is not possible and thus the rear wheels will start spinning regardless because the rear-axle is connected to the drivetrain at all times. Obviously, torque transferred to the ground is all at the front wheels (called torque appropriation according to this), but the inertia of the rear-axle will always be engaged.

[JohnVidale]

Originally Posted by drob23

Yes, this confusion is easy to see. You never want to the wheels to slip because this lowers the coefficient of friction (sliding vs non-sliding) and thus makes a loss of traction situation even worse. Not to mention, if the wheel is spinning uncontrollably at high speed, I imagine if it hits a patch of road with high friction it could apply a very strong yaw moment and cause you to lose control. I'm no expert on vehicle dynamics, but this is my intuition.

In the scenario you present, assume the front wheels have good traction while the rear wheels are on ice (somewhat academic example I suppose). In this case, you do not want any torque to be transferred to the rear wheels. Ideally, the center differential would route all torque to the front wheels and the rear wheels would roll without slippage. In the case of xdrive, this is not possible and thus the rear wheels will start spinning regardless because the rear-axle is connected to the drivetrain at all times. Obviously, torque transferred to the ground is all at the front wheels (called torque appropriation according to this), but the inertia of the rear-axle will always be engaged.

I guess my point is that, whether the back wheels are spinning or not, the torque is being applied 0/100 between the back and front wheels in this case. So the torque would NOT be applied at best 50/50.

It would be preferable to have the back wheels spinning at just the point of slipping, although if the front wheels have traction, the back wheels likely should be rotating at a similar speed, not much slower. In fact, spinning at a similar rate to the front wheels offers the best chance to gain traction.

I read the linked section on "torque split ratio". It seems to be defined as the ratio of the rotation rate of the front and rear axles, which is NOT the apportioning of the torque between the axles. So maybe the "torque split ratio" is at most 50/50, but that does not mean the slipping rear wheels are doing less than the optimum thing.

[drob23]

Originally Posted by JohnVidale

I guess my point is that, whether the back wheels are spinning or not, the torque is being applied 0/100 between the back and front wheels in this case. So the torque would NOT be applied at best 50/50.

It would be preferable to have the back wheels spinning at just the point of slipping, although if the front wheels have traction, the back wheels likely should be rotating at a similar speed, not much slower. In fact, spinning at a similar rate to the front wheels offers the best chance to gain traction.

Yes, this is why I said

Originally Posted by drob23

Obviously, torque transferred to the ground is all at the front wheels (called torque appropriation according to this), but the inertia of the rear-axle will always be engaged.

note "torque appropriation" vs "torque split".

I'm no expert on drivetrains, so take my answer with a grain of salt. I don't think that the wheel speeds are coupled from the front and back - that would be the purpose of a locking differential. I understand that torque can be routed backwards through the drivetrain - ie engine braking - but I don't think your hypothesis holds.

You will likely see lots of wheel spin from the back wheels in our example, which is not the ideal solution. In practice, the rear wheels will never be on a frictionless surface - thus the purpose of the center differential (or clutch) is to route power in a manner that prevents any wheel from slipping. XDrive has less authority to do this since the front wheels can never be turned with a mechanical advantage greater than the rear wheels.

Crap...I really need to get back to work

[drob23]

Originally Posted by JohnVidale

I read the linked section on "torque split ratio". It seems to be defined as the ratio of the rotation rate of the front and rear axles, which is NOT the apportioning of the torque between the axles. So maybe the "torque split ratio" is at most 50/50, but that does not mean the slipping rear wheels are doing less than the optimum thing.

I think the issue is with this example of frictionless back tires. Assume the ideal torque split should instead be 60-40 to prevent slippage due to road surface and put all the torque down that you can ( ie maximize acceleration(t)). In this case, the 50-50 split will either force the rear wheels to spin or force the driver to engage less throttle. It doesn't matter how the "torque appropriation" is carried out, it matters how much of the available torque is actually applied to ground from the engine *without* causing the wheels to slip.

[seis-speed]

Originally Posted by RPM90

If you really want and need AWD I'd say go with the S4.
Audi's quattro is excellent.
Plus quattro actually improves the cars overall handling and performance whereas X drive lessens the 3's overall handling performance, at least in my experience and in reading reviews of X drive 3's.
Not saying X drive is bad. One benefit, besides allowing better snow driving, is that it helps off the line acceleration.
It's just not the famed BMW RWD performance, whereas quattro is what makes an Audi and Audi.

For the best handling 3 series I'd go RWD.
For the best handling Audi A4/S4 I'd go AWD.

The S4 is one very sweet sport sedan. I had an A4 sport 2006 and it was very fun to drive, GREAT in the snow.
Not as nimble as my 325i, 135i, or current 335i, but fun non the less.
The S4 is a stellar sport sedan. It readily beats the former and current 335i in performance reviews.
Awesome V6 supercharged engine. Equally kinda numb steering as the F30, but just as responsive and accurate.
Sport suspension feels a bit firmer than my 335i Msport, and I would prefer a firmer feel in my 335i.
Mechanically and driving/handling is as good as my 335i Msport, and maybe even a bit better.

But, what stopped me from getting the S4 was the seating comfort and a good bit higher lease payment for nearly the same MSRP and selling prices.
The S4 sport seats are quite nice, but they just sat too high and wouldn't go lower and I needed them too. I felt like I was sitting ON the car instead of IN it. That sucked as I put driver seat comfort as the #1 priority on my list of 'need/must have'.
Also, MPG isn't as good with the S4 compared to the F30 Xdrive and especially RWD 335i with sport AT.
Leasing was awful for the S4.
My 335i Msport has an MSRP of around $52K and with good negotiating and decent BMW incentives and great lease rates my monthly is around $512 tax included.
The S4 would have been in the mid $600's.

When you equip and option an S4 with an equivalent 335i Msport the 335i is more expensive.
335Xi Msport - MSRP: $54,520
335Xi Sport - MSRP: $53,020
S4 - MSRP: $52,470

The S4 is an excellent choice for an AWD sport sedan.
The 335Xi is also an excellent choice.
But since you asked which one, I pick the S4 for an AWD sport sedan.

This is what I am wondering. I am a skier, I do not need AWD for daily use, but I do not want to switch cars with my wife who drives the X5. I actually bought the X5 for me, but I am just a manual car guy I neeed a sports car feel in a practical AWD sedan IN MANUAL ONLY. Eliminating the need for me to have two cars, one for play one for driving.

[seis-speed]

Originally Posted by drob23

I edited the values for curb weights for the various BMW 3 series models with AT, as they were somewhat wrong. Interesting how there's about a 300lb difference between a 328i 6MT and 335ix AT. The gulf between an S4 and 328i MT is huge and will definitely be MUCH different in terms of driving dynamics - especially in corners.

But the 335ix drive is only 200lbs lighter than the S4, and with the weight balance thrown off with the heavier engine/x drive equipment, I would think there won't be too big of a difference between them. I've actually read some complaints about xdrive understeer when exiting corners, since the xdrive will clutch power towards the front when applying heavy throttle at moderate speeds. The ZF rear torque vectoring on the S4 is the star in this situation, which is designed specifically to combat the understeer without applying brakes on the inner wheels.

The sensation of RWD vs AWD is what really distinguishes the two. The vehicle pitch due to RWD acceleration is awesome, you can't argue with how satisfying it is. The S4 feels more like a pull, and while it is probably overall harsher and faster, it doesn't cause you to lean back like the 3 series (but it definitely puts a smile on my face ).

Since you have had both cars, do you notice the weight? Does the Audi feel sporty to you, is it nimble, do you have a manual? Thanks.

[drob23]

Originally Posted by seis-speed

Since you have had both cars, do you notice the weight? Does the Audi feel sporty to you, is it nimble, do you have a manual? Thanks.

Sadly, at this time of year the only cornering I'm doing is on/off the highway, so no, I don't notice the weight (only had the car for a month or so). I have the adaptive suspension package, so in dynamic mode the car feels very aggressive and stiff on the highway. I have the DSG, so the driving experience is different than a 6MT. I will say the S4 feels harsher day to day, probably due to the comfort of the torque converter in the ZF8 - very smooth AT compared to the DSG.

Based on what you've said, if you want to track and have the faster car, the S4 would be the choice. Else, if you don't need AWD then I'd go with a 328i/335i because it'll be the sportier feeling car day to day (RWD of course being the culprit). You will not realize the shortcomings of the drivetrain until after you take it to a track - which a stiffer suspension + rear LSD should solve your problems (at which point you're encroaching on the M3). The 3 series will also get you better fuel economy if that matters. Just borrow the wife's car for your ski trips...

Hell...you could even wait for a 55k 3200 lb C7 corvette with a rev matching 7MT. Thing is supposed to be 0-60 in high 3 seconds?!?!

[dd1981]

Originally Posted by webdither

I test drove the S4 twice.

- Felt heavier, bigger, less nimble
- MUCH more expensive lease payment. Residual was not as good as BMW.
- (opinion) F30 looks better inside and out
- That silver painted plastic around the instrument cluster was a huge turnoff, looks cheap
- S4 body style is OLD now. Likely to get a complete overhaul before the end of a lease, rather get the all new look of the BMW.

^this

The door panels felt cheap, the dealer wouldn't budge on the price...quite frankly they were a bunch of know it alls. Plus BMW is better quality and the f30 looks 10 times better.

[DesertSmokeBBQ]

I have a 2011 S4 as well as a 2013 F30 328i M-Sport. I initially went into Audi North Scottsdale to look at either a 2013 S4 or S5 but 36mo lease was $150/mo more than my current lease payment with FEWER options (buying at invoice). North Scottsdale BMW occupies the same piece of real estate and a line of F30's was 10ft away so I wandered over on my way out. I ended up with a 2013 F30 M-Sport in EBII w/premium/heated seats/paddles/EBT AND a significantly lower payment (at invoice minus 5% of holdback). I decided on the 328i vs 335i because a quick call to Dynocomp confirmed stage 2 tune of 325hp and 70fps torque AT THE WHEELS would run me $1200. 335i performance with a but over $10k saved

[seis-speed]

Originally Posted by drob23

Sadly, at this time of year the only cornering I'm doing is on/off the highway, so no, I don't notice the weight (only had the car for a month or so). I have the adaptive suspension package, so in dynamic mode the car feels very aggressive and stiff on the highway. I have the DSG, so the driving experience is different than a 6MT. I will say the S4 feels harsher day to day, probably due to the comfort of the torque converter in the ZF8 - very smooth AT compared to the DSG.

Based on what you've said, if you want to track and have the faster car, the S4 would be the choice. Else, if you don't need AWD then I'd go with a 328i/335i because it'll be the sportier feeling car day to day (RWD of course being the culprit). You will not realize the shortcomings of the drivetrain until after you take it to a track - which a stiffer suspension + rear LSD should solve your problems (at which point you're encroaching on the M3). The 3 series will also get you better fuel economy if that matters. Just borrow the wife's car for your ski trips...

Hell...you could even wait for a 55k 3200 lb C7 corvette with a rev matching 7MT. Thing is supposed to be 0-60 in high 3 seconds?!?!

No tracking, it is a DD, will not switch with the wife. Hahaha. I will get AWD rather than switch.

[drob23]

Originally Posted by seis-speed

No tracking, it is a DD, will not switch with the wife. Hahaha. I will get AWD rather than switch.

Hehe, ok well if you have hard constraints of AWD luxury sports sedan that you plan to finance/buy - I'd say go S4.

But ultimately, assuming your local dealership has some S4's with sports differential, you need to test drive each one and decide which one will be more viable for DD duty. The idrive blows away the MMI and the HUD is really cool, but I think the Audi interior is much nicer with alcantara (I also swapped LED's inside) and the DRL's look straight nasty from head on. I really like the individual setting for drive select - you can tailor specifically the cars feel - I prefer stiff suspension, nominal shift maps/throttle response, aggressive sports diff, nominal steering and conservative engine noise (silly speaker I think). I also prefer the more subtle styling of the Audi. The F30 has more rear seat room if that matters.

If you go BMW and you're picky with options, chances are you'll need to custom order. BMW offers more competitive pricing and lots of incentives if you qualify (check out the ordering/pricing section). Audi cars have their trim levels - in this case only 2 - and from there not much optioning can be done. But if you have to order an Audi it could take a looooonnnngggg time, so be prepared to drive to a distant dealership if you want a specific S4.

[webdither]

At the time I was looking at the S4 Audi Drive Select was only an option on the Prestige model and was a $4k+ option on top of that. Talk about sticker shock! It could have just been a configurator bug at the time because now it appears the adaptive suspension and sports diff are now available on any S4 at a more reasonable price. If the car I wanted was under $60k at the time I was looking I might have put more effort into negotiating but it was so far out of the ballpark of an equally equipped F30 that it wasn't an option. It does appear that Audi has adjusted to be more competitive.

[drob23]

Originally Posted by webdither

At the time I was looking at the S4 Audi Drive Select was only an option on the Prestige model and was a $4k+ option on top of that. Talk about sticker shock! It could have just been a configurator bug at the time because now it appears the adaptive suspension and sports diff are now available on any S4 at a more reasonable price. If the car I wanted was under $60k at the time I was looking I might have put more effort into negotiating but it was so far out of the ballpark of an equally equipped F30 that it wasn't an option. It does appear that Audi has adjusted to be more competitive.

Wow, that's a ridiculous pricing for drive select

Now you get audi drive select when you order the sports differential at 1.2k. The adaptive suspension is an additional 1.2k which requires the differential. In fact, many of the bare bones offerings have simply 6MT and sports differential bringing the price just south of 50k msrp. Most of the other options are luxury in function with the exception of 19" rims.

[f30ca]

http://www.f30post.com/forums/showpo...4&postcount=58