Gone off track The pointless discussion on FWD vs RWD from G45 X3 thread

[MercFan]

MLB is developed as an AWD-first platform for Audi/Porsche's unique generally rear-biased AWD. It is FWD in it's basic form, but of course the FWD/AWD won't behave like a RWD car taking off a turn. It is quite a different platform than your typical FWD economy car platform (complex multi-link front suspension, longitudinally mounted engine, center and rear diffs, etc)

You can definitely still get the rear to kick out though and Audis have quite stiff chassis in general. You do feel the rear-bias especially on spirited drives... I went from a RWD E90 to a AWD B8.5 A4 so yeah I know what I'm talking about. OBVIOUSLY it won't kick out/drift like a RWD but you can get it a little lose with late trail-braking and weight transfer techniques.

That's wrong. You can make any AWD rear biased. Let's remember SUBARUs from the 90s with their DCCD system. It could be front biased, neutral or rear biased just by turning a switch.

Of course the front multilink MLB in theory is better than McPherson MQB. But we all know that the first 911 with double wishbone was a 992 GT3. All that came before this - McPherson)

The platform has nothing to do with how an FWD car will handle. Only the differential setup, suspension kinematics and tires.

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In this video you can see how just the change from the OEM 4S to the normal 4S makes an M3 understeer.

 

[martinbo]

I'd rather do it in an A4)

Ok, each to their own. I rather would not. I don't like the feeling of the front wheels scrabbling for grip because they're both driven and doing the steering.

I don't see much difference.

I see, and feel, a significant difference. Even FWD-based AWD is easily discernable from RWD. Just is.

 

[martinbo]

Let's remember SUBARUs from the 90s with their DCCD system. It could be front biased, neutral or rear biased just by turning a switch.

Nope. This is a common misperception and has been often incorrectly reported as enabling a rear-biased torque differential. It does not.
What it does is increase the rate of differential locking at the centre differential between the front and rear axles. I know this, and have experienced this extensively with hundreds of track hours behind the wheel of Subarus, because I was an instructor for them for 12 years. It's well documented on this forum.

 

[MercFan]

So wait a min, I'm a victim of ignorance, but you're pointing to a POS GM car that was FWD as evidence of FWD being as expensive to build as RWD just because they priced it at certain level? That is sheer ignorance. You also left out the fact that GM later on switched the entire Cadillac lineup BACK to RWD because their cars were utter shit and being killed by all the RWD based competition. There goes that.

You keep trying to conflate two issues. I said that RWD is more expensive to build and you keep pointing to how the MLB EVO platform is used in a Porsche as to imply there is no difference between a RWD and FWD architecture when it comes to driving. I'll say it for you again, PORSCHE IS AN EXCEPTION. Not sure what you aren't getting. This is not the first time they're taken pedestrian underpinnings and made something better. That is an OUTLIER, not the norm. That they chose to build all those vehicles on that platform only proves my point that it was a cost decision.

If there was no difference between FWD and RWD, why wouldn't all the high end luxury car makers used FWD to free up more space in their cabins?

The only one that is ignorant is you if you think their is no difference between FWD and RWD other than some space in the cabin.

M

I jumped to conclusions with ignorance. An ignorant person can learn. You can't.

To sum up:

Merc1 DOESN'T HAVE any numbers to prove that FWD platform is cheaper in development or in production than an RWD platform.

Merc1 KNOWS NOTHING about Cadillac but tries to argue and talks nonsense) Eldorado was FWD from 1967 to 2002! How much "later" did General Motors switched back?) Maybe they "switched" for the cost cutting? Making some premium cars on an RWD platform and some on an FWD - is expensive. And where is the success after Cadillac switched?) To make it clear, in 1967 the cheapest car you could buy in the USA was Ford Falcon on the "premium" RWD platform)))

Built on the FWD platform Cayenne and Urus are the better handling SUVs than GLE63 or X5 M built on an RWD platform. That's it!

Porsche can't be an "exception"! What an idiotic statement! They didn't make it better! They didn't even develop MLB platform. It was developed by AUDI! Porsche just made their car on it. Some harder bushings, other shocks settings, sharper steering. Less comfort. The same chassis! Like Lamborghini.

You don't even understand that the car industry itself started with a RWD because it is more simple and easier to maintain. Have you ever heard about Ford T? It has a "premium" RWD platform)))

 

[MercFan]

Ok, each to their own. I rather would not. I don't like the feeling of the front wheels scrabbling for grip because they're both driven and doing the steering.

I see, and feel, a significant difference. Even FWD-based AWD is easily discernable from RWD. Just is.

How do you feel the difference in a full time AWD car if it has 40/60 torque distribution?

You can feel the difference because the tuning engineer put exactly these behavior into the car. Nothing else.


P.S. On a slippery surface I would definitely choose front wheel drive if we talk about safe driving. It's better.

 

[MercFan]

Nope. This is a common misperception and has been often incorrectly reported as enabling a rear-biased torque differential. It does not.
What it does is increase the rate of differential locking at the centre differential between the front and rear axles. I know this, and have experienced this extensively with hundreds of track hours behind the wheel of Subarus, because I was an instructor for them for 12 years. It's well documented on this forum.

I drove a Subaru with DCCD on the gravel. It was rear biased. I was told that I could make it neutral any time I want.

 

[martinbo]

I drove a Subaru with DCCD on the gravel. It was rear biased. I was told that I could make it neutral any time I want.

Alright then, believe what you want. Let's get back on topic to the G45 X3. I'll move these rambling posts elsewhere.

 

[Merc1]

I jumped to conclusions with ignorance. An ignorant person can learn. You can't.

To sum up:

Merc1 DOESN'T HAVE any numbers to prove that FWD platform is cheaper in development or in production than an RWD platform.

Merc1 KNOWS NOTHING about Cadillac but tries to argue and talks nonsense) Eldorado was FWD from 1967 to 2002! How much "later" did General Motors switched back?) Maybe they "switched" for the cost cutting? Making some premium cars on an RWD platform and some on an FWD - is expensive. And where is the success after Cadillac switched?) To make it clear, in 1967 the cheapest car you could buy in the USA was Ford Falcon on the "premium" RWD platform)))

Built on the FWD platform Cayenne and Urus are the better handling SUVs than GLE63 or X5 M built on an RWD platform. That's it!

Porsche can't be an "exception"! What an idiotic statement! They didn't make it better! They didn't even develop MLB platform. It was developed by AUDI! Porsche just made their car on it. Some harder bushings, other shocks settings, sharper steering. Less comfort. The same chassis! Like Lamborghini.

You don't even understand that the car industry itself started with a RWD because it is more simple and easier to maintain. Have you ever heard about Ford T? It has a "premium" RWD platform)))

The problem is that you haven't learned anything and you seemingly don't have basic common sense. Any automotive source will tell you that RWD costs more to develop and manufacture than FWD. This can easily be googled, while you ask for some numbers that you know can't be had without hacking into these various companies servers.

I know more Cadillac than your lame wikipedia search will ever tell you. WTF does the Cadillac Eldorado being FWD prove? NOTHING. They switched to RWD when the foreign competition starting kicking their arse that is when they did. Now you're saying "maybe", no you need to provide facts and numbers like you're asking me to do, not some "maybe". In 1967 most cars were RWD because, we're talking about 2024, not 1967, again irrelevant comment.

GM, Ford, Chrysler all switched to FWD in the 80s for nearly everything they made due to it being cheaper to design and manufacture. This is a fact. Smaller FWD was they way they survived and it also got them killed in the market when it came to luxury vehicles. You think the Chyrsler K cars were just as expensive to build aa Mercedes or BMW in the 80s that where RWD? Now that's idiotic.

Cadillac switched their entire car lineup back to RWD over the years because FWD was vaslty inferior for the sport sedan theme they were chasing. Anyone that knows anything about Cadillac will tell you this. They also switched to FWD in the late 70s and 80s to save money and it nearly killed the brand.

"Built on the FWD platform Cayenne and Urus are the better handling SUVs than GLE63 or X5 M built on an RWD platform. That's it!"

That doesn't have anything to do with which is more expensive to build. Like are you not able to understand that? You keep talking about handling, that wasn't my point from the start. And again this platform is not your typical FWD layout that something like a Civic or Camry uses.

Porsche is that exception today because no one is using such a platform build high end vehicles on. So you think Porsche just took the platform and put their body on top of it and called it a day? That belief would make you idiotic. So now you have the engineering details on what Porsche did to to this platform?

So your argument for RWD being so cheap to produce is so piss poor that you have to go back a 100+ years to a Ford model T to make a point in 2024? That is the dumbest thing I've seen posted here in a while. That absoulutey has nothing to do with today. Yeah because a Ford Model T was cheap to build in 1908 a 3-Series or 5-Series or 7-Series must be cheap to build in 2025 = just plain stupid.

M

 

[Tuffode]

At least two rear tires changes each summer season with no power sliding or burnouts.

That doesn't sound right, unless you are doing like 60k miles a summer. I drift and do burnouts like a maniac but still get at least 20k out of Michelin's.

 

[Matski]

I'll never forget, back in my late teens (the late 90s), when I'd starting lusting over 80s Bimmers, but was condemned to driving my little Pug 106 (because insurance). I was driving around a roundabout near my friends house, on the grip limit as it nearly always was (because I drove like a twat, and the car only had 50 hp, did 0-60 in 20+ secs, but had skinny wheels and weighed about 800kg), and leaving the roundabout ahead of us, was an E32 735i, he absolutely booted it as he exited the roundabout just as he crossed from positive camber tracking to the right, to positive camber tracking to the left. We saw the back-end twitch, and both instantly reacted with an exclamation something akin to a 'f#ck yeah' cheer... yet the 7-ers progress remained 'confident', and seemingly otherwise really planted.

For reference, this was the piece of road I'm on about (in 2009).. with the camber change exaggerated in green...

It was only a small thing, but in my adolescent mind seeing a slightly dated business saloon give a hint towards actually being on the edge of dynamic composure in such a way was cool as ****. Within 12 months I'd decided to ignore the fact that buying an old Bimmer would be mean a higher insurance premium every year than the cost of the car, and bought my first BMW, an E28 528i. Even in my 3 speed auto 635, I always kept that 7-er in mind when I was booting it for mechanical kickdown off roundabouts.

26 years later and I'm still only driving RWD Bimmers. I cannot imagine thinking that RWD isn't better, if you like driving, even in urban environments. That's not to say I think FWD is inherently bad (there are FWD cars I lust after), but it absolutely sure as shit isn't the same.

 

[Design FIRST]

This then 20 year old idiot lost the rear end of a Type 105 Alfa-Romeo 2000 GTV Bertone coupe (not mine) on a remote slick with rain and mud, late autumn country road. I was pushing far too hard and grossly overrated my competence as a driver. I went rear first into a potato field, I was immensely lucky to have gotten away physically unscathed, both the car and myself, from that embarrassing act of idiocy. Embarrassing as hell although I was alone in the car and there were very few motorists on the road. But it was a good practical lesson regarding the physics of abrupt weightload shift in RWD cars. A totally different sort of, far more belligerent animal than with FWD vehicles.

 

[Matski]

But it was a good practical lesson regarding the physics of abrupt weightload shift in RWD cars. A totally different sort of, far more belligerent animal than with FWD vehicles

My 106 would get significant lift off oversteer as there was basically no weight to the back end of the car at all. I've actually performed far more heroic looking slides and 'drifts' when driving like a pillock in that FWD 106 than I have done in all the rest of my Bimmers. The 106 also saw ferocious and highly frequent use of the handbrake to adjust the car orientation which is something I've not done once since trading up to a RWD car. It's only the 635CSi that could break traction easily at the back end - and that's because the millimetric TRXs were terrible, all the rest of the BMWs I've had have required a level of commitment to loosing the back end that I'm far too sensible to try and demonstrate since leaving my teens..

... except this one time in my 520i, when I picked up some tell-tale vegetation during my trip through the bushes.