The 2012 BMW 328i is the first example of the all-new 6th-generation 3 Series sedan (code name: F30) we've had in the shop.
It's hard to tell with the naked eye, but the footprint of BMW's volume seller has grown significantly. Longer overall by 4.3 inches, it now rides on a wheelbase that's 1.9 inches longer. And even though its overall width has shrunk by a scant 0.2 inches, the U.S.-spec 2012 328's tires have been spread farther apart by 1.2 inches up front and 2.3 inches out back. Despite all this, the curb weight of a 328i manual only increases by 44 pounds.
In CAFE terms, the footprint has been increased 5 percent, from 44.8 square feet to 46.9 square feet. That's interesting because cars with bigger footprints have less aggressive fuel economy increase targets. And the new CAFE standards only regulate the footprints you build in a given year, not the footprints you built last time out. At least in part, this size growth may be an example of strategic upsizing for CAFE purposes.
But such regulatory talk is boring. Let's see the metal.
Along the way you might want to open my walkaround of a 2009 BMW 3 Series in another window. That one was an M3, so you'll see more aluminum, but you can still see how the basic architecture differs...or doesn't.
Even though the detail dimensions are different, the basic 3 Series suspension philosophy remains. This is still a strut-based front suspension.
As before, this is a "dual link" strut, in that it uses two distinct links (green), each with their own ball joint, instead of a single lower control arm and one lower ball joint.
The front stabilizer bar is direct-acting via an elongated stabilizer link (yellow) that connects directly to the strut housing.
The key advantage of this arrangement is the ability to move the virtual steering pivot point outboard to a spot that would be physically impossible with a single ball joint. This in turn allows the engineers to reduce the scrub radius and do other cool things with steering geometry. Of course the "instantaneous virtual" intersection point shown above is constantly moving, so figuring it out properly is a bit more complicated than just overlaying a couple of yellow lines.
Pretty neat, huh?
Among all that aluminum there's a front suspension height sensor (green) and we can just see the bottom of the twin-tube front strut (yellow).
One of the "tells" that gives away the twin-tube strut is this (green) flattened section for tire clearance. And this mechanism (yellow) shows that this 3 Series is equipped with the "Adaptive M Sport" suspension with electronically controlled dampers. The height sensor we saw previously is one of several inputs that feed into the controlling ECU.
The 328i's brakes, meanwhile, are comprised of single-piston floaters (green) and ventilated rotors. One of the openings in the front grille (yellow) brings in cool air.
Peel back the diagonal hood seals on either side and you'll find a strut tower brace (yellow) that ties into the firewall.
Hard to tell what's going on in back from this angle. Nicely finished wheel well, though.
The rear of the new 3 Series is propped up by a 5-link multilink setup that's similar, but not identical, to last year's. It's almost impossible to see all five links in one shot, but we'll eventually catch up with all of them.
As we've seen many times before, the two upper links (green) approximate an upper A-arm. The forward-most of the two lower links (yellow) is visible, but the rearmost one is not because it's behind the shock. The slender link at the rear (orange) is the toe link.
From this vantage point we can see the missing link (yellow), a massive affair that also carries the spring and shock absorber. The toe link (green) we saw in the last shot sits just above it. Both of them have eccentric cams built into their inner attachment points; the lower one is for camber and the upper one is for toe.
This head-on view of the same links shows the eccentric cams a bit more clearly. It also shows us the motion ratio of the spring to be about 0.60-to-1 and that of the shock to be about 0.85-to-1, not unlike the outgoing generation.
The underneath view (my new favorite) shows just how the two lower links work together. None of this was all that visible until I first removed an aerodynamic cover that fastens to four tiny bolts that surround the spring pocket.
A smallish (but big enough) rear stabilizer bar (green) snakes between the upper links on the way to meet its own drop link.
That link is made of high-grade plastic and has ball joints on both ends. It attaches directly to the knuckle at a 1-to-1 motion ratio.
Right next door stands another twin-tube shock with electronically adjustable damping.
Wherever there are computer-controlled shocks there will also be suspension position sensors.
This view from the front shows the axle and the rear diff housing.
All of the 2012 BMW 328i's rear links are steel, but don't expect that to remain the case when we eventually see the M3 version of the F30 3 Series, whenever that is.
Like the front, the rear end of the 2012 BMW 328i is hauled down by single-piston sliding calipers and ventilated rotors.
Any 2012 BMW 328i equipped with the optional Luxury Line, Modern Line, Sport Line or the M-Sport package will, among other things, do away with the base model's 17-by-7.5-inch wheels and 225/50R17 tires in favor of 18-by-8-inch wheels and 225/45R18 rubber. In accordance with BMW habit these days, the tires are run-flats.
As you can see, the mounted 18-inch setup weighs 53 pounds per corner. Compare that to the 2009 BMW M3, where larger 265/40R18 tires and wider 18-by-9.5-inch rims weighed just 52 pounds. What's the difference? The M3's tires were not run-flats, which made them lighter. And before you go there, no, I don't think our M3 had forged wheels; we had settled for the standard 18-inch configuration instead of the optional 19-inch combo. If true, the difference we're seeing here (or lack thereof) is mostly down to tire weight.
Even though run-flat tires are not the best choice for unsprung weight and have not been a fan favorite for ride or noise in the past, the lack of a spare nevertheless helps BMW reduce the 3 Series' dyno "test weight" for CAFE measurement and fuel economy labeling purposes.
Dang. We're back in the midst of that regulatory stuff again. Sorry.
Photos by Scott Jacobs
Animation by Mark Takahashi
miamifan1 says:
07:35 PM, 02/13/12
Wow that rear suspension is all sorts of complex! whatever...it works great. bmw really goes the extra mile.
love the animation too. its hypnotizing, so cool.
blueguydotcom says:
08:49 PM, 02/13/12
Drove a 2012 328i Modern Line on Sunday. Not impressive. Car feels huge on the inside and the Modern handles like a damned land yacht. Guessing the sport will be better but it won't change how absolutely huge the 3 feels inside now. Makes the jumbo-sized e90 feel tiny.
frazier500 says:
09:10 PM, 02/13/12
@blueguydotcom
You really had me until you called the E90 jumbo-sized. I'm glad it's getting bigger honestly, it needs to compete with the A4. This coming from an E46 owner, too.
agentorange says:
09:54 PM, 02/13/12
In the animation the strut appears to move fore and aft as well as turn. How is that movement accommodated, by rubber? Also, look at the amount of movement in the shorter of the two links. Is there a Heim joint at the inboard end?
isend2c says:
10:01 PM, 02/13/12
this will probably be one of the best handling cars on the market... I hope that the complexity of the suspension is not destined to break, but suspension is normally fine... I was left with a bad taste in my mouth about things that went wrong with my SMALL E90.
kyolml says:
10:30 PM, 02/13/12
it's pretty close to the e90 suspension design, not revolutionary.
I am really interest in the CAFE requirment Dan talked about. Where can you find the relationship between size and required fuel economy increase? what do you mean build by given year instead of last time out?
hondacura4 says:
11:14 PM, 02/13/12
I'm usually only interested in the higher trims such as the 335 and the M3 but this new N20 turbo 4 and its proposed performance and fuel economy is simply fantastic.
hondacura4 says:
12:52 AM, 02/14/12
Blueguy, I wish BMW would consider producing a 1 Series sedan for U.S. consumption as I fell in love with my cousins 2011 BMW 135i ///M sport convertible. That Twin Power inline 6 was fantastic as well as the DCT. Interior space was much better than I expected given how small the car is on the outside. I never felt cramped at all and I'm all legs. Very nice package overall.
joefrompa says:
04:13 AM, 02/14/12
Thanks Dan. The suspension walkaround for me was "so so" - it's well engineered, but I've been more impressed at lower price points too. And this is now mostly old hat.
What struck me more is that this is a suspension that will not age well come 8-10 years from now. There are absolutely a ton of rubber ball joints and key plastic components sitting exposed to the elements and potholes.
In 2020, the first f30s are going to want to get a $2000 makeover in control arms, lateral links, end links, bushing press-ins, and suspension positioning sensors.
I guess that's normal, just struck me how prevalent it was here.
...
I find the f30 to be the first "right sized" 3-series I've been in - all others were small to me. It's close to the e39 5-series, which I've always found ideal.
I'm very excited to drive my first f30 328i 6-speed manual with sport package. I have driven a wide variety of BMWs over the years and I've found them consistently dissapointing to drive unless they are manually transmission'd and sport package'd - so I've learned not to drive them otherwise for impression purposes.
The 328i is offering an amazing level of performance + economy. This thing is now as fast as an e36 m3 or a e46 330i ZHP while offering about ~8mpg more on the highway. This is the base model - simply an awesome feat.
ctpaul says:
04:43 AM, 02/14/12
great write up, really enjoy these, thanks!
nefariousnigel says:
05:26 AM, 02/14/12
So BMW thinks that the skinny, black donut, garden-variety TEMPORARY spare tire will really destroy their CAFE dyno test? Really? That justifies heavy riding, heavyweight run flats? This is the best engineering solution they have?
If you believe this, you're a sheep. This was someone's brilliant mandate from the top that the engineeers are forced to live with.
This baloney PR would be bad enough, but then Dan just HAD to throw in the 'regulatory stuff' comment? C'mon man, can't we get a break from anti-government knobs in the suspension walkaround?
Aside from that, it is a gorgeous setup - but frankly after test driving a Camaro SS on 20 inch rims along some well potholed Chicago area streets, it will take more than pictures of a bunch of aluminum links to impress. I was shocked at how well the big old heavy pony car rode...literally absorbed hellacious potholes that I thought would shudder the car - or worse - damage the rims/tires.
I'm not saying the 328 won't do the same - it is just that suspension bar, like everything else, has risen impressively in other models/brands.
blueguydotcom says:
06:06 AM, 02/14/12
@Joe - they didn't have a 328i with sport and finding one with manual... well that seems like a herculean task. They'll call when a sport comes in.
@honda - yeah, 1 series hatch/sedan would be ideal, in my view. I've got no need for a sedan as massive as the F30. Reminded me of my dad's old crown vic.
jeepsrt says:
06:17 AM, 02/14/12
"What struck me more is that this is a suspension that will not age well come 8-10 years from now. There are absolutely a ton of rubber ball joints and key plastic components sitting exposed to the elements and potholes."
I disagree, we sold our 2001 BMW 330Ci in october 2010 and it was just as tight as when it was new.
saunupe1911 says:
06:30 AM, 02/14/12
That's a word class suspension and this is a world class article. Articles like these make you want to go out and buy a 328i. Plus MotorTrend says that it handles better than the 335 and its only .4 seconds slower to 60. The 328i is freaking awesome. That ATS better be darn good because the 328i is.... regardless of its reliability history.
roadburner says:
06:55 AM, 02/14/12
"I disagree, we sold our 2001 BMW 330Ci in october 2010 and it was just as tight as when it was new."
Ditto for my 1995 318ti(131,000 miles) and 2004 X3(129,000 miles).
duck87 says:
06:55 AM, 02/14/12
@miamifan1/isend2c: The macpherson strut front and multilink rear setup is pretty common nowadays. You see this in cars like the Civic and Mazda 3 too.
@agentorange: Not sure if it's heim joints, I'm pretty sure that's just rubber bushings flexing. The fore/aft movement is in part created by the fact that the strut moves with the hub (as in most macstrut suspensions), and the strut's inclination (and resulting scrub radius)... when you steer the car, the hub pivots around the strut and moves forward and back a bit as a result; the two links and their virtual pivot actually reduces this effect quite a bit (desireable). A good reason why you would want a double wishbone suspension is because they locate the wheel better and you can control this movement much better.
frank908 says:
07:09 AM, 02/14/12
I see they're now using the wheel-well liner made totally of rigid felt like Mini does. Quells noise, but is a magnet for road debris.
fordson1 says:
08:13 AM, 02/14/12
VERY interesting front suspension, with the pivot point moving forward and back. Now, that would be moving forward and back in a straight line rather than an arc, right? I mean, the track is not wider with the wheels pointed straight ahead, is it?
NOT impressed with BMW wheels anymore - lots of issues surfaced by the notorious C&D long-term 5-series car, and every BMW long-term test lately has had the testers bending and replacing wheels.
For your 2009 M3 that you reference, you did not spring for the forged wheels...in what universe is it OK to sell a $65k M3 with cast wheels? The new 370Z you folks looked at the other day, for probably $35k or $40k, had forged wheels on it...Ray's forged wheels.
Especially with the higher impact force that the heavier run-flats will create (higher unsprung weight), and more concentrated impact area, due to the stiffer run-flat sidewalls, I would say forged wheels are a no-brainer. This is bad, harmful decontenting.
The other thing is, how far up the 3-series food chain do you have to go to get a fixed front caliper with pistons on both sides?
blueguydotcom says:
08:48 AM, 02/14/12
@ford - M3s do not use RFTs. They had the cast wheels but regular tires, not RFT junk.
duck87 says:
08:58 AM, 02/14/12
@fordson1: yeah, I'm seeing an arc, but it's very slight... only a few degrees. Then again, you have to remember that wheels on both sides are pivotting, so the track wouldn't change a whole lot.
joefrompa says:
09:03 AM, 02/14/12
Roadburner and JeepSRT -
I can't comment on your experiences nor your locales. Up here in the northeast, I don't think those would be the cases.
I can tell you that on the BMWs I have evaluated, most needed to be freshened up in the suspensions by ~8-9 years in terms of lateral links, endlinks, and struts - if it had not already been done. Usuaully a minimum of struts (which is normal) and one lateral link or control arm and endlinks.
This f30 has the usual assortment and then introduces some new extensive use of plastic. My experience with plastic in the suspension is that it's less durable than the metal/rubber in the northeast.
agentorange says:
10:35 AM, 02/14/12
@joefrompa
"I find the f30 to be the first "right sized" 3-series I've been in - all others were small to me. It's close to the e39 5-series, which I've always found ideal."
Sorry, Joe, then by your definition it is clearly too big. A 3-series the size of an old 5-series is no longer a 3 for me.
witnessx says:
11:36 AM, 02/14/12
I thought the new 3-series had a double wishbone front suspension like the F01 and F10. Oh well.
You're right about the M3, wheels, BTW. The standard 18s are cast, the standalone 19s are forged, and I believe the 19s from the Competition Package are forged as well (but don't quote me on that last one).
6sptl says:
11:45 AM, 02/14/12
Single piston front brakes, Mc Phearson front suspension, mostly stamped steel suspension components, if this werent a BMW everyone would be pointing out what crap components this car uses, hate fanboys...... BTW the double articulation of the front struts has nothing to do with handling its to enable a wide steering angle so as to avoid the curbs in narrow european streets and parking spaces.
csubowtie says:
12:14 PM, 02/14/12
I like that front suspension. Trying to characterize the kinematics of it would be a bitch though. Very cool animation as well.
mfennell says:
01:19 PM, 02/14/12
@agentorange: "Sorry, Joe, then by your definition it is clearly too big. A 3-series the size of an old 5-series is no longer a 3 for me."
Amen to that. I still have a really nice E30 318is. It's smaller than a Sonic sedan.
Have to admit, you can't complain about the drivetrain progress though. This big-as-an-E39* 3 series gets considerably better fuel mileage than my 140hp E30.
*OK, not quite as big. The F10 is 1" wider but 6" shorter and has a 1" shorter wheelbase.
e90_m3 says:
01:54 PM, 02/14/12
re: agentorange,
Thank goodness they sell the 1 series here. Clarkson on his DVD said the 1M is the car he enjoyed the most. That the 1M is in the company of a 458, McLaren MP4, and others is a huge endorsement of the 1M. He also waxed poetic all over the 135 in his newspaper column.
Last time I took my 535 in for service, I told my SA the 5 is car I need while the 1 is the one I want. The SAs around us couldn't agree more.
icemilkcoffee says:
04:18 PM, 02/14/12
Wait a second- is there any adjustment possible on the front suspension? You mention the 2 eccentrics in the rear, but nothing for the front, and I don't see to see any eccentrics anywhere in the front. This would be a big mistake on BMW's part.
roadburner says:
09:02 PM, 02/14/12
Nice enough, but a bit too big. If I stick with Munich I'm going with either an M Sport 1er, an E46 M3, or a Z4 M Coupe.
But a Cayman is looking better all the time...
joefrompa says:
06:19 AM, 02/15/12
When's the road test coming?
auaq says:
08:59 AM, 02/15/12
I'm a bit worried about the bushings on the overall suspension joints. I wonder if BMW have done something about them because in about 9-10 years they start to wear out and cause steering vibrations on certain speed and then chassis vibrations as well, as I just have right now on my e39 530i. I will be replacing them soon with the powerflex polyurethane bushings probably this week. Also, I'm bit concerned about the high grade plastic stabilizer links. However, I think they did the right thing of going to steel made rear axle frame.
andrew20195 says:
10:09 AM, 02/15/12
What kind of vehicles do you people drive that don't have worn out suspension after 10 years? That's pretty much part of owning an older car.
@fordson1: Forged aluminum is stronger than cast aluminum by weight. This allows manufacturers to use less material for a lighter wheel with the same strength as a heavier cast wheel. Cast wheels themselves are not necessarily less resilient than forged wheels.
x_defector says:
10:32 AM, 02/15/12
Cool - I think I see a bit of the magic here. As the rear suspension droops it looks like it toes out a pretty good amount....and conversely toes in under compression. Almost a bit of 'passive rear-steer' effect. Pretty cool stuff.
As far as the 'plastic' comments.... that ain't no regular plastic. That's FRP, its rigid as hell and will hold up to use and abuse at least as well as steel counterparts, maybe better.
magbarn says:
10:53 AM, 02/15/12
6sptl says:
11:45 AM, 02/14/12
Single piston front brakes, Mc Phearson front suspension, mostly stamped steel suspension components, if this werent a BMW everyone would be pointing out what crap components this car uses, hate fanboys......
The sad thing is that it still rides heckuva lot better and with much better steering feel than your fancy 'double-wishbone' TL. The Japanese still haven't gotten close to the mix of handling/ride quality that BMW's got.
duck87 says:
07:00 AM, 02/16/12
@x_defector: Most cars employ that effect with a multilink rear. A good reason why torsion beam suspensions suck in cheaper cars is because they can't control this movement as well.
bimmerjay says:
08:39 AM, 02/16/12
@fordson,
"The other thing is, how far up the 3-series food chain do you have to go to get a fixed front caliper with pistons on both sides?"
The F30 335i has standard fixed multi-piston calipers and larger rotors.