Z4M v. E89 sdrive35is

[Spaceman Spiff]

Sorry of this has been covered before.

I am considering an upgrade and have been looking at E89s for a few weeks, mostly 35is but also 35i. Z4M seems like a very reasonable alternative, with better performance (albeit not as torque-y) and considerably lower price. However, given that it's an older car (and an M), I was wondering what the maintenance costs would be like on a 2006-7 model with around 50K miles, which seems to be the typical for-sale Z4M profile. Also, is there a specific model year to look for?

[The HACK]

Considering that the N54/N55 engine needs a $500-800 valve cleaning every 30,000 miles and $100 worth of spark plugs every 45,000 miles, the maintenance on the M isn't any more expensive than the 35is depending on how often you change your oil.

[Spaceman Spiff]

Thanks man! That sounds perfectly reasonable for the 5k miles or so that I drive every year. Another question: Is there a reason not to go supercharged? A couple of cars currently available here are supercharged and it's very tempting!

[donoman]

Any time you run boost you are wearing the engine internals faster than without. It's not exactly "free" power as you will decrease your reliability. How much? Enough that it matters? That's a harder question to answer. If you're only driving 5k per year might not be too bad...

[pokeybritches]

It depends on whether you have more time or money. You can't beat OEM in terms of reliability and fit/finish. A supercharged car requires more knowledge of the car and a lot of DIY. You'll need a knowledgable performance shop to service the car.

The blower on my M has been largely transparent other than the massive increase in power. The 3.0i has been a different story. If you don't need the car as a daily driver, supercharging is great. I would personally take a supercharged M over a newer Z4, no doubt about it. I don't know about buying a used car with aftermarket FI though. The car must have a very thorough inspection at a shop of my choice.

[pokeybritches]

Since the question of boost killing the life of an engine has come up before, and I've got a few minutes to burn...

Running a stock engine to 8k rpm will cause more wear and tear than boosting it to 6-8 psi and running to 5k rpm, assuming the car is properly tuned and sorted.

There are many facets to an engine's mechanical limits; each type of stress comes with its own possible failures. High rpm requires an engine to have good tensile strength, and boosting an engine requires compressive strength. Because the heat from compression makes fuel quality the first limit encountered with a tuned engine under boost (aka detonation), the S54 is proven to have more than enough strength to handle the compressive loads. I'm admittedly simplifying it, as boost = bigger boom = more torque = potentially more wear on other components (like oil being squeezed away from bearings)... but my point is that you will probably encounter a failure from other loads or wear and tear before the additional stress from boost culminates into catastrophic failure. You should be more concerned with revving to 8k rpm than boosting to 6 psi. Replace your rod bearings several times through the life of the engine, add a blower, and enjoy the S54's awesome sky-high redline.

IMHO, there's no need to deny yourself certain satisfactions for fear of additional wear and tear, when another culprit is likely to be the death of the engine. Colin Chapman (Lotus) once said that the perfect racing car would win a race and then fall apart on the finish line. I've treated my cars the same way - boost up to the point that everything will wear out at the same time... best guess at least

[David70]

Originally Posted by Spaceman Spiff

Thanks man! That sounds perfectly reasonable for the 5k miles or so that I drive every year. Another question: Is there a reason not to go supercharged? A couple of cars currently available here are supercharged and it's very tempting!

From a value standpoint it doesn't seem like what the car is worth goes up much considering what it costs to supercharge it. Depends on how long you plan on keeping the car and how much you would enjoy the extra power. Buy a Z4M, supercharge it and sell it next year and it becomes an expensive year of use.

[ZStig]

I think buying a used supercharged Z4M is great bang for the buck. Not doing it yourself for $9k unless you keep the car supercharged for 3+ years. Then when you pro-rate it, it makes sense

I've actually considered a Sdrive35 + exhaust + tune as a replacement vehicle, because its a lot more refined for daily driving. The poor resale of an 81k mile supercharged Z4M keeps me from trading that way

[Vanne]

From all accounts I've read on the e89, it drives and handles like a wet blanket.
Do yourself a favour and go drive one for a bit before buying one.

[Spaceman Spiff]

Thanks everyone!

So to sum it up: Supercharged may need more frequent maintenance and not be as reliable as a daily driver, but won't make much of a difference in engine life?

I will be using the car as a daily driver so reliability is certainly a factor. That said, the additional power/torque is still very tempting. I think I'll continue to look at stock engines but may go for a clean supercharged. Is there a specific kit that's been more reliable than others?

W/r/t E89, I agree that it is just not a purpose-built sport car. Every review that I have read says it's a step away from a true roadster and toward a comfortable cruiser like the SLK. It's a shame as I really like the design

[Huz-Z]

Based on the above, If you are tracking the car I would think an E85M would be the best choice . But for a daily driver an E89 might do the trick for you.

[XMetal]

Originally Posted by Spaceman Spiff

Thanks everyone!

So to sum it up: Supercharged may need more frequent maintenance and not be as reliable as a daily driver, but won't make much of a difference in engine life?

I will be using the car as a daily driver so reliability is certainly a factor. That said, the additional power/torque is still very tempting. I think I'll continue to look at stock engines but may go for a clean supercharged. Is there a specific kit that's been more reliable than others?

W/r/t E89, I agree that it is just not a purpose-built sport car. Every review that I have read says it's a step away from a true roadster and toward a comfortable cruiser like the SLK. It's a shame as I really like the design

To further rain on you parade...Unless you "know someone", you will have a very tough time registering a supercharged Z4 in California.

[yousefnjr]

35is: no manual, no LSD, no thanks

[Schlesien]

Amen

[chickdr]

Originally Posted by Spaceman Spiff

Thanks everyone!

So to sum it up: Supercharged may need more frequent maintenance and not be as reliable as a daily driver, but won't make much of a difference in engine life?

I will be using the car as a daily driver so reliability is certainly a factor. That said, the additional power/torque is still very tempting. I think I'll continue to look at stock engines but may go for a clean supercharged. Is there a specific kit that's been more reliable than others?

W/r/t E89, I agree that it is just not a purpose-built sport car. Every review that I have read says it's a step away from a true roadster and toward a comfortable cruiser like the SLK. It's a shame as I really like the design

The thing is it appears you currently have a 2.5i motor right? Going to the stock 3.2 M motor will be a HUGE boost in performance. Heck, a 3.0si would be a massive gain on its own over the 2.5. I assume you have driven an M to compare with your car?

[The HACK]

I PERSONALLY wouldn't touch a FI car that didn't come from the factory that way. Unless you know the person who did the work and are intimately familiar with the work done, and know exactly who tuned it, aftermarket FI engines are just TROUBLE.

Not saying I wouldn't consider an MZ4 that's supercharged. I just wouldn't consider one that I don't know the history of.

[R0ME0]

If you're gonna go with the Z4M at 50K make sure S2 has been done (~$1500-$2000 job)! The dealer never did it when I picked mine up and lied about when it needed to be done. My bad for not doing better homework. But honestly you'll be happy with both can't go wrong. Inline 6 Raw NA power or the N54/N55 with some bolt ons are a blast! Finding a 35iSdrive in Manual though thats a chore!

[KevinM]

The sDrive35is is not available with a manual - game, set, match for the MZ4C. The 35i is available (I think) with a manual. But if you've not driven both, one drive will tell you which one you want. I have never driven two cars that are similar in size and shape that have such different operating characteristics and feel.

[chickdr]

Originally Posted by R0ME0

If you're gonna go with the Z4M at 50K make sure S2 has been done (~$1500-$2000 job)! The dealer never did it when I picked mine up and lied about when it needed to be done. My bad for not doing better homework. But honestly you'll be happy with both can't go wrong. Inline 6 Raw NA power or the N54/N55 with some bolt ons are a blast! Finding a 35iSdrive in Manual though thats a chore!

Yes, an impossible one!

[Spaceman Spiff]

Originally Posted by chickdr

The thing is it appears you currently have a 2.5i motor right? Going to the stock 3.2 M motor will be a HUGE boost in performance. Heck, a 3.0si would be a massive gain on its own over the 2.5. I assume you have driven an M to compare with your car?

I have and it was great! It is definitely a huge step above my 2.5 but that supercharger sounds so tempting!

Yet it seems like I'll be getting a stock one, given all the input from everyone here. Going to check one out this week. It's a 2006 roadster with 30K miles which is lower than everything else I have seen. Wish me luck!

[chickdr]

Originally Posted by Spaceman Spiff

I have and it was great! It is definitely a huge step above my 2.5 but that supercharger sounds so tempting!

Yet it seems like I'll be getting a stock one, given all the input from everyone here. Going to check one out this week. It's a 2006 roadster with 30K miles which is lower than everything else I have seen. Wish me luck!

It is an '06 M roadster? Best of luck.