BMW 3-Series 2005 and earlier

shipo · May 2001

Tchoo,

Time to dust off my old car mechanic hat from 25 years ago. I am no chemical engineer, but it is my understanding that the higher the octane the more stable the fuel is when heated and under pressure and the cooler the burn. Hence, engines with higher compression ratios (hotter air/fuel mixture pre-spark, more efficient combustion post-spark) actually get more power from premium fuel. The general rule of thumb (my thumb has been getting quite a workout these last couple of days) is to use the lowest grade of fuel that your engine was designed for.

With modern ignition systems, that rule has gotten a little fuzzy, but it is still a good idea to follow it for several reasons:

The earlier your engine can fire the spark plugs relative to the position of the piston the more heat you generate, the better the thermal efficiency. The better the thermal efficiency, the more power you get from a given amount of fuel, that yields either better power or better economy (or a combination of both).

Ignition systems can only retard so far, if you have a very high compression engine (10.5:1 or better) you may actually damage the engine by using a lower grade of fuel in anything but "Limp Home Mode". That means that if you have no other option, use the low octane fuel and then yield to the Little Old Lady in the 1975 Granada.

Higher-grade fuels usually have extra detergents and other additives that help your engine stay clean and produce full power for a long period of time.

A few years ago, it seemed that the reverse situation was happening, people would buy a fairly pedestrian automobile that was designed for low-grade fuel and then put Premium in it. The thinking was that Premium would give them better power; this cannot be farther from the truth. In reality, the low compression (8.0:1) will not generate enough heat to assure complete combustion of the stable high octane fuel, this results in deposits made up of combustion by products being left all over the inside of the combustion chamber and the valves. If the driver persists in using Premium on such a car, it would become a self-fulfilling situation. With enough deposits, one will eventually form as a small narrow spike, it will get hot and start glowing, then, the only way to keep from blowing a hole in a piston or blowing a valve up into the head is to continue using Premium. Eventually, even that will not be enough. I seem to remember a guy over at the local airport filling up his Yugo with 100LL aviation gasoline. ;-)

Brave1heart,

;-)

Best Regards,
Shipo

tchoo · May 2001

Don't get me wrong, I defintely intend to use Premium in my car, especially since the 2.5L engine has a higher compression ratio. Why skimp on a few bucks on a $30K car?
This was an interesting tech sessions on fuels though. Glad we have such a wealth of knowledge here.

denright · May 2001

How long was your car in 112 status before hitting 150? I am trying to figure out when I can expect my car to hit 150, as it hit 112 this past thursday.

brave1heart · May 2001

Well, you guys sound so impressive on this topic, you could write a book. You forgot to mention one minor detail, though. What kind of gas would you recommend for the 3-series? If shipo is correct (I wouldn't fight that battle) by saying that you should go with the lowest grade your engine is designed for, doesn't that mean that 91 would be better than 93? 91 is the minimum octane level that BMW recommends.

Filling up a Yugo with 100LL aviation gasoline - LOL. That's classic of the same caliber as that guy who called technical support to complain that the cup-holder that his PC came with just broke. Yep, it was the CD ROM he was talking about and it was a true story, just like the Yugo.

brave1heart · May 2001

tcn2k · May 2001

This morning while driving to work, i saw the m3 alpine white; some guy was driving it. The front headlights looks very similiar to the '02 3 series i saw of pic floating around this board.

jasonkureejii · May 2001

I didn't know the compression ratio was such a factor. How do the engineers decide what octane-level to use and based on what dimensions, i.e. if compression ratio is one, say. Otherwise, it's all interesting, but I think I'll stick to what was recommended.

deepdarkblu,
I don't know how much of a difference it's going to make if I'm awaiting a 325i, but I know that my dealer had the purchase request in on 5/17, a Thursday. By 5/22, my car was already in 151 status. It is now in the paint shop and due to be completed by 6/8, if not earlier. It's 2 weeks ahead of the proposed schedule.

I know there was a discussion on 325s produced at the South Africa factory, right, and I didn't mark anything, unfortuantely. I'm even unsure where my car is being produced...still. I think I will give BMWNA a call again. BUT, if it is being produced in SA, is there anything I should be aware of. Has anyone here had one produced from it and were even the slightest concerned. I don't think I should be.

e46avatar · May 2001

Thanks for the info, ya saved me a whole lot of elbow grease.

good luck on the sound system. Let us know you like it.

dhanley · May 2001

I know of some guys who have a dinan shop, and they claim that the inline 6 makes the same spark curve if you use mid or high octane fuel, so i use mid--it's a little cheaper, it should burn a little hotter ( reducing deposits ) and make a little bit more power.

Dinan's chips ( as well as conforti and others ) work partially because they advance the spark, which requieres premium.

If i were driving like a nut on a very hot day, i might fill it up with premium.

Write a book? Thanks. I think fiction and computers are my game.

dave

thedeepdarkblu · May 2001

brave1heart · May 2001

I was thinking that you should be able to arrange with your dealer to have them swap the 17" wheels with the 16's if you think the 17's are too much for a sedan. This way you get the firmer ride, lowered suspension, and fabulous seats in a more conservative-looking package. I love the 17" wheels but I can understand it if a more mature person thinks they are too much. They dealer should be willing to do it, as you are essentially trading more expensive wheels for cheaper wheels. BTW, the '02 330i is getting the style 44 wheels - same ones from the '01 325i SP and the 325ci SP. Obviously, there are a lot more people out there who think that the style 44 wheels are great looking.

taos2 · May 2001

I live and drive and 6-7K feet. Octanes offered
in this part of th country are lower than what's
found in Houston for example.

On my first test drive of 3-Series here in
Albuquerque, the salesman specificly stated that
all their vehicle used and were filled with
regular 85 octane. When I pressed him about what
the factory recommended he still insisted that
regular was adequate and the dealer stood by that.

burrsr · May 2001

You're right -- inertia does not vary with velocity (independent of velocity). What I should have said is that momentum ( = mv) becomes less sensitive to mass as velocity increases. The higher the v, the less m contributes to momentum. So a 1500 kg car at 1 m/s has 100 kgm/s more momentum than a 1400 kg car at that same speed. However, at 100m/s, that same car now has 10,000 kgm/s more momentum than the other car -- all due to the change in v. This is also why cars' rates of acceleration decrease with increased velocity -- constant force (roughly) applied to a constant mass, but more momentum to overcome. Not to mention other factors that increase (some exponentially) with speed, such as wind drag and other frictional forces.

Which is why we should all use the minimum octane that the engine is designed for (91 for 3ers, I believe)...

thedeepdarkblu · May 2001

Not absolutely sure, as this waiting has become a blur for me--translation, everything seems just plain too long. It was slated for June 1 production or thereabouts, so it looks like it's pretty much on schedule.

thedeepdarkblu · May 2001

I can't even remember when I placed my order, somewhere at the end of April. If yours went into production status that early, I'd say you bought the guys in Munich some very good beer. I feel like I've been waiting forever.

brave1heart · May 2001

I see what you guys mean. At increasingly higher speed, the same absolute changes bring less relative changes, right? Example: adding 1 to 2 is a 50% difference. Adding 1 to 50 is only a 2% difference. The higher the speed, the less the acceleration difference due to weight between otherwise equivalent models because we are working with smaller relative changes. It's that simple.

emilyk · May 2001

I've seen several spy-shots of the upcoming 2002 3-series, but today on bimmer.org, I found a full blown frontal shot. Is this the M3? Or is it really a 330? Can anyone enlighten me?

http://www.bimmer.org/3series/messages/archive/msgsy2001w22/34968.html

aaa330i · May 2001

I think your car might be a south african build. I hope not...that would mean a couple extra week delay. Did you ever get a response back as to what the N on the VIN meant?

burrsr · May 2001

Yes, that is correct in a simplifed way of looking at it. I'm just glad to be able to APPLY this stuff after 10+ years of learning it...

So, have we figured out the optimal octane rating for our 3ers? If it's 91, then I'm pumping in a couple octane ratings too high and wasting a couple dollars/month in the process. I don't care about the extra $5/month, but I DO care about engine longevity and performance optimization! Is it 91 or 93??? Shipo -- you seem to be the most knowledgeable about this topic -- any further insights?

emilyk · May 2001

I figured BMW would eventually decide to switch back to the style 44 wheels for the 330. I wasn't going to order the SP on my 330 because the sport suspension was standard and I preferred the 4-spoke steering wheel of the non-SP. However, when I saw those hideous radial wheels on the non-SP 330, I decided to order the SP for the M-double spokes. The radials are a pain to keep clean.

thedeepdarkblu · May 2001

I'm not too keen on the new styling, if that is, in fact, the way the new 3 will look. It changes the very things that don't need changing. The grille looks bad with the pointy outer corners. The previous kidney bean grille was perfect. This photo also shows a front-heavy and bulbous front spoiler w/ the fog lights moved up to the actual bumper. I don't think it looks very cohesive or attractive. It's the answer to a question that nobody asked.

JingleJill · May 2001

I am taking my 330i into the shop this weekend for its 15k service.

I love the car and I don't think I have any problems with it, but the more I think about it, I think I could.

Anyway, I've driven standards for 10 years; honda, nissan, mazda, ford... All of them have been easier and much smoother than the BMW. I am not sure if it is because it is rear wheel drive or what, but when I shift, the noise is loud, like a clunk and it is rarely smooth; at least from 1st to 3rd gear.

So, this gets me thinking... is this normal? I don't remember the car I test drove to be that "rough", but it has been 9 months or so.

I have read comments where people have said the car needs to be broken in, etc... and things only get better. Well, 15k miles later and mine doesn't appear to be getting better.

Not only that, but does anyone have a hesitation when pressing the accelerator? Sometimes, the car just doesn't want to move. Where is all the power?

Okay guys (and ladies) help me out here. Am I paranoid? I'd like any suggestions so that when I take the car in on Saturday I can speak to the service advisor with some knowledge of what I am talking about.

Suggestions are welcome... appreciate it.

Thanks,
Stacy

GLeen · May 2001

Please explain why you all own the 3 series over the 5 series?

Thanks.

brave1heart · May 2001

emilyk - this is not the M3 - it does not have the distinctive M3 side vents. I can believe it is the new 330i. Well, let's see what the changes are: same color molding for the sedan, fresher grill, halo lights from the 5-series, better-looking wheels - yeah, a few cosmetic changes to keep it looking fresh. It's nice but it looks a lot more like a downsized 5-series and it is les distinctive that way. I would not wait for it if I were to buy right now. Not unless there is a substantial discount over the '01 MY models (very unlikely) and you can get the same dealer discount as on the MY models (even more unlikely). You are saying "back to the style 44 wheels"? I didn't know they used the 44s on the 330 in the past...

alpine325i · May 2001

Brave1heart: I don't know enough about Dinan, but my dealer reccommended the Dinan mods. He said any other type of mods would void the warranty. The mods that were on my previous cars were: Performance Choice Cold Air Induction, Hypertech stage 3 chip, and the Flowmaster 2 chamber muffler Cat-Back Exhaust System. 2 chamber mufflers are loud and agresssive and are less restrictive. 3 chamber mufflers are deep and mellow and a little more restrictive, but add alot more airflow compared to a factory muffler, way more!. Music? The first CD I popped in was Yanni and John Tesh, with special guest Kenny G! Then "Who Let The Dogs Out!" (just kidding). First song was Pat Metheny's "Are You Going With Me" from one of his live albums that I downloaded off of the internet. Then Linkin Park for some updated hard rock. Then the 80's hits radio station. Hmmm.. The 80's... The land of pastel clothing and Pac Man, but it was alot of fun!

)

langley2 · May 2001

I asked the same question of both my dealer and BMW North America. Both said that while the car WILL run fine on 87 octane, long-term use will probably adversely affect the engine. The dealer also told me that some people think they can use 87 octane most of the time and then add a tank of 93 octane once in a while to "clean" out the system. Bad move. Apparently doing this messes up the catalytic converter and causes strong hydrogen sulfide type fumes to back up into the interior of the vehicle. He also told me that the car IS actually spec'ed for 91 octane, so 93 is really something of an overkill. Said 89 octane (mid-grade) is a good compromise and is close enough to 91 to allow the car to run well with no danger of engine damage.

That said, however, I do remember reading a post a while back stating that use of 93 octane does increase fuel economy, so it might just be worth spending the few extra cents per gallong after all.

thedeepdarkblu · May 2001

Well, some of us have a car spending budget (like me). Others may like the styling better. I also chose the 3 b/c the 5 doesn't have a coupe version. But, again, it's mostly about price, I think.

brave1heart · May 2001

"Anyway, I've driven standards for 10 years; honda, nissan, mazda, ford... All of them have been easier and much smoother than the BMW". ?!?!?!?!?!?!?!?!?!?!? I am afraid I can't help you here. You should sell your 40-grand Bimmer and buy a honda, nissan, mazda, ford. Your boyfriend might be happier you got rid of that overpriced, underpowered German car.
As far acceleration, there isn't a whole lot of it under 1,800 RPMs - you should specify what RPM level you feel that at.

emilyk · May 2001

I recall that BMW used the Style 44 wheels on the 328 of years past, however I could be mistaken.

brave1heart · May 2001

3 is lighter, faster, more agile, more fun to drive, easier to toss around, equipped the same, plenty spacious for me (6'1, 205 lbs) and well, 10 grand cheaper.

brave1heart · May 2001

You are right about the 328 but I thought you were talking about the 330.

brave1heart · May 2001

I can't keep up with this speed of posting

)

alpine325i · May 2001

Wow, if that's what the new 330i is going to look like, I'm sold! Beautiful! I guess I'll have to start saving up now for a decent down payment. I just hope they don't overprice this one like I thought they did with the 01's. Hmmm... lets see.. new stereo.. Dinan... That stuff might have to wait!

)

brave1heart · May 2001

"Yanni and John Tesh, with special guest Kenny G" - man, my jaws dropped so hard for a second, I thought I was going to break them. You really scared me there - can you imagine these three guys putting a concert together for real? What a long-haired, warm and fuzzy love fest.

BTW, I love your 'Mods and Music' motto. It's almost like the Romans' 'Bread and Circus'!!

motorcity3 · May 2001

Wow, all these posts. Thanks everyone for your informative posts on my octane question. I do agree that 91 as stated by BMW would be good, but my choices here are 87, 89 or 93. So far I have been using 93 and I think I will stick with it. Now......did anyone ever consider turning off the DSC (in dry conditions) to get better acceleration? If they did, did the car handle much worse?

JingleJill · May 2001

Sell the car? NEVER!!! It truly is the ultimate driving machine. I drove the other cars until I could afford the BMW. I admit, I am spoiled by the car. Don't know if I can ever go back to anything inferior, which would be everything? ;o)

When I drop my car off for service, I was going to see if I could drive another 330 to see if there is a difference or if I am paranoid.

In all seriousness though, it just doesn't seem "normal". (Then again, what is normal?)

Stacy

GLeen · May 2001

My local BMW dealer said that all 3 series are selling at MSRP, 5 series $2k below, and 740 name your price. Does this seem accurate as fas as the 3 series goes?

motorcity3 · May 2001

Wow, all these posts. Thanks everyone for your informative posts on my octane question. I do agree that 91 as stated by BMW would be good, but my choices here are 87, 89 or 93. So far I have been using 93 and I think I will stick with it. Now......did anyone ever consider turning off the DSC (in dry conditions) to get better acceleration? If they did, did the car handle much worse?

raybear · May 2001

I'm seeing discounts on three's. Depends on where you're looking.

aaa330i · May 2001

You're dealer's full of it...or they're the only one in town and are taking advantage of it. I got my almost fully loaded 330i for $1500 over invoice (not MSRP). I've even eard of a few people getting it for $1300 and $1400. Ask around or use the Rizzo method when it's time to buy.

alpine325i · May 2001

Yanni, John Tesh, Kenny G, That IS a scary thought! LOL! I call that category of music "crooning for secretaries", or "people that are dead from the neck up".

)

aaa330i · May 2001

I'm going to be playing Jo Dee Messina's Heads Carolina, Tails Californa when I pick mine from the dealer.

burrsr · May 2001

Of BMW's model lines, the 3ers are the least discounted. The 3-series is the most popular and in-demand of the lines, and it is really BMW's bread and butter. They do not have to discount much on them, as supply and demand economics wins out. However, many folks on this board have been able to get prices of $1,500 to $2,000 above invoice (or about the same dollar amounts below MSRP in this case), so derals are there to be had. It depends heavily on geographic regions, # of dealers in the area, time of the month, life cycle of the model, Jupiter's moons' alignment, etc., etc. What surprised me most when shopping is how (relatively) little (percentage-wise) the cars are marked up from invoice to MSRP. Also, due to the high demand of the 3er, I have seen no manufacturer incentives from BMW to the dealer. The only exception to this is some money factor subsidizing on 330i sedans, which obviously applies to leases only.

Given the current auto market conditions and the fact that MY 2002 cars are soon to come, I would anticipate dealers to loosen up a bit over the next few months.

aaa330i · May 2001

brave1heart · May 2001

denright · May 2001

Sure, why not?

denright · May 2001

Stricken by Braveheart!

brave1heart · May 2001

Better chances there than the stock market judging by today's developments :0)

brave1heart · May 2001

Stick around for 5000 - better luck then. 5000 is a bigger number anyhow and at that speed of posting, it will take us what - a couple of days only?

BMW 3-Series 2005 and earlier

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