328i versus M3 weights

[knifegun]

I searched and did not find a answer for the following question.

Why is the E90 M3 360 lbs heavier than its 328i counter part? Based on the BMW USA specifications, the 328i weights 3362 lbs while the M3 weighs 3726 lbs.

Links:

http://www.bmwusa.com/Standard/Conte...fications.aspx

http://www.bmwusa.com/Standard/Conte...fications.aspx

[JonnyM3]

V8
Suspension parts
Wider Body

There are many things that add weight

[ScheerSpeed]

What he said

[aajami]

The suspension parts on the M3 are all aluminum, so I have to assume that they're lighter.

The S65 is lighter than the S54 it replaced, though I wouldn't be surprised if it was heaver than the 328i's I6.

The CF roof on the M3 should be lighter.

The M3 has wider panels than the 328i, but I have a hard time believing that the panels themselves are heavier.

Exhaust is heavier. Wheels and tires are heavier. DCT transmission is heavier. Power seats are heavier.

[calintexas]

To know for sure, you'd have to do a component by component weight inventory. The 328i does have the magnesium block engine, smaller brakes, and I'm pretty sure a lower torque capacity (lighter) drive train. Generally more powerful versions of a specific car model are heavier because of the stronger/larger components required to deal with the extra power and stop the car safely. Standard option content between the 328 and the M3 is likely a factor also.

[smmmurf]

Bigger engine, which in turn needs more cooling, holds more fluids (oil and coolant), bigger wheels/tires, larger brakes, larger headers/exhaust system (m3 exhaust weighs 50+ lbs for just the rear section), etc.

[knifegun]

Makes sense. I had incorrectly assumed that part of creating the M3 would be to use lighter materials to make up for the additional components. But I had not thought about the fact it may require more fluids and stronger components to handle the extra power.

I have tracked my car a few times and it feels so heavy. While the EDC is nice for normal driving, it is way to soft for even casual track use. The brakes don't seem to be great either when tracked. Makes me wish the car was lighter or that the suspension had more aggressive settings along with better brakes (at least upgraded brake pads that don't melt and leave deposits on the rotors).

[JIO]

The trick differential on the M3 adds some serious weight also.

The M3 only gets lighter when you compare the M3 driver's wallet to the 328i driver's wallet.

[mkoesel]

Originally Posted by aajami

The S65 is lighter than the S54 it replaced, though I wouldn't be surprised if it was heaver than the 328i's I6.

It's heavier than the N54 even, so it's definitely heavier than the N52.

Exhaust is heavier. Wheels and tires are heavier. DCT transmission is heavier. Power seats are heavier.

Of course, the M3 has manual seats standard now. But yeah, clearly they didn't adjust the curb wieght figure to account for that though. DCT is also not standard equipment though.

OP's question is a good one. Though the official numbers are often disputed for the M3, the fact remains that 300 lbs more than the 328i does seems pretty excessive. It would be interesting to weigh a completely stripped (factory stripped I mean, not post factory weight savings mods) M3 vs. a completely stipped 328i.

[Richbot]

Brakes are a big one. Also all those M3 badges. Suspension is heavier, the regular E90's already used aluminum everywhere and the narrower track means smaller parts. When you add power you have to slow it down and turn it, and make sure you're not going to break anything in the process. Ferrari's lightest model is heavier than a 328i right now because of that phenomenon. Adding lightness is great and the best way to improve all aspects of a car's performance at once, but the diminishing returns start early when you're talking about a street car. Good thing is, most of the added weight is low in the car. 300lbs of lead in the roof wouldn't be nearly as fun.

EDIT: 328i also doesn't come with HIDs as standard, that's about 20lbs right there.

[mkoesel]

Originally Posted by Richbot

EDIT: 328i also doesn't come with HIDs as standard, that's about 20lbs right there.

Seriously, 20lbs extra for HIDs? I would never have guessed that. Why are they so much heavier than standard halogen lights (or whatever BMW is using)?

[Richbot]

It's a total ass-pull from what I know the E46 halogens weighed relative to OEM HID's.

Halogens on the E90 are just like any other car's lights, they're not adaptive, they don't auto-level, they just sit there and throw out light.

In addition to normal halogens, the OEM HID assemblies have -
-Auto-leveling actuators
-Dynamic (left/right) actuators
-Projectors, which are heavier (physically bigger to house the projector)
-Ballast/ignitors
-More seals/joints/hardware/wiring
-Physically bigger overall housing

It was a little under 10lbs per side on the E46 sedan parts I weighed and that wasn't even the dynamic xenons, just auto-leveling. Of course just slapping an ebay HID kit on a car probably only adds 2lbs but BMW thankfully (or unfortunately, depending on whether you like spending $2k on a failed headlight) didn't go that route.

[mkoesel]

Good points - I hadn't really thought about all the added tech in the HID lights. It's just one more place where progress and added gadgetry contributes to the overall bloat of modern cars. Not that I don't like my HIDs of course. It's just easy to forget the ugly side of all this tech.

[Richbot]

I'll never own another car without them. LED's are supposed to be lighter for the same light output but I read that they need cooling fans. Please BMW, don't give me another cooling system to work on every 50k miles...

[mdosu]

Originally Posted by calintexas

To know for sure, you'd have to do a component by component weight inventory. The 328i does have the magnesium block engine, smaller brakes, and I'm pretty sure a lower torque capacity (lighter) drive train. Generally more powerful versions of a specific car model are heavier because of the stronger/larger components required to deal with the extra power and stop the car safely. Standard option content between the 328 and the M3 is likely a factor also.

what he said. Performance parts were added to the car. The tranny is different, the differential is different, engine is different, wheels are larger and probably weigh more.

[kmarei]

plus the POWER, EDC, DSC switch

[Crazy Bimmer]

Sound deadening adds weight as well. M3 is much quieter in the cabin than my 328 or 335i were.

[Erhan]

Originally Posted by aajami

The suspension parts on the M3 are all aluminum, so I have to assume that they're lighter.

Yes but they are also strenghten. That adds weight.

Originally Posted by aajami

The S65 is lighter than the S54 it replaced, though I wouldn't be surprised if it was heaver than the 328i's I6.

Anything can be lighter than iron block S54

[Erhan]

Originally Posted by mdosu

wheels are larger and probably weigh more.

The 245/265 wheels with APEX wheels I had for my Z4MC was pretty much 50lb per corner. Sure the tires in 328 also has some weight but when you think about it, 4 tires&wheels are already 200lbs of the 3700lbs curb weight.

[CLS]

Some of the dumbest people on earth are concentrated in this forum.

Originally Posted by erhanh

The 245/265 wheels with APEX wheels I had for my Z4MC was pretty much 50lb per corner. Sure the tires in 328 also has some weight but when you think about it, 4 tires&wheels are already 200lbs of the 3700lbs curb weight.

[Erhan]

Originally Posted by CLS

Some of the dumbest people on earth are concentrated in this forum.

And with you in the board, we can claim to be number 1.