Pros/cons of 23i/30i/35i

[Smartbear]

It’s not necessarily the power or torque of the six that appeals to me on its own. It’s more the smoothness of that config.
Yes it’s got some oomph but also very smooth and relaxing when the mood takes you .Smoothness that a four cylinder engine can never achieve.

I’m not sure how many n20 engined z4’s you’ve owned Ron? I’ve had a couple of 3litre z4’s and the 2litre runs extremely smoothly-you can’t feel it running when driving.
Bmw fitted this engine with twin balance shafts to achieve this.
The smaller/lighter engine also makes for a more agile car compared to the heavier 6pots, this has all been discussed many times on here
Rob

[B21]

It’s not necessarily the power or torque of the six that appeals to me on its own. It’s more the smoothness of that config.
Yes it’s got some oomph but also very smooth and relaxing when the mood takes you .Smoothness that a four cylinder engine can never achieve.

The smoothness of an in-line 6 versus an inline 4 is based on the assumption that both these engines do not use any supplementary devices as part of NVH minimisations.

In the case if 4 cylinder engines there has been now many decades of engineering refinements to address this issue.

Smoothness is measured in many different dimensions..primary balance, secondary balance, torsional vibration etc etc

So the actual smoothness of a power plant is based on many factors way beyond the simple theoretical argument of 6 cylinders are smoother than 4.

As someone who ran a N20 powered E89 and a N54 powered E89 side by side for 8 months..sometimes swapping daily.

I can say without doubt that the N20 powered car felt smoother under almost all circumstances than the N54 powered car.

If people want to buy a N52/N54 powered version for reasons of emotion, like an engine bay filled with engine or any other thing that floats their boat that’s great..

But the smoothness logic is flawed and not valid.

[ronk]

None!

Only ever owned BMW sixes so probably not the best judge!
I’m thinking back to previous 4cyl Mercedes I’ve owned - never been in a z4 - 4cyl car

Im not bothered what it looks like with the lid up! It’s just a bit of plastic cover.

[Nictrix]

I actually think that our 23i was slightly smoother than our 35i.

[Pondrew]

Having an N20, and a B58 in the household, and previously an N54, I can honestly say I've never noticed any difference in 'smoothness' in any of them.

We are not talking about Merc S classes here, so can't really see the relevance.

The OP said he needs reasonable running costs, as the car will be a daily. N20 all day long if those are the criteria.

[Jellybaby38]

Thanks everyone - lots to think about, especially with the engine.

As said previously, decide what are essentials and what are desirables then stick to your plan if you’re able

this is a very good point, but possibly hard to stick to My only real essentials are iDrive and Ski hatch, which makes it easy to discount things quite quickly, but then leaves a limited selection.

Just watch for SE Highline spec cars advertised incorrectly, they have Msport seats but no iDrive so can be seen easily.

I reckon 90% of the Highline specs advertised on Autotrader, etc have exactly this problem especially from dealers.

I personally wouldn't buy any of the 6 pots if those are your needs [...]
Would be interested to know what budget you are thinking of?

From a fuel cost point of view, over 4000 miles using the average MPG of the 20i 4pot vs the 30i 6pot, there's about £250 difference based on today's super-unleaded price. That's fuel alone and doesn't take into account reliability of the engine. Any stats for maintenance costs would be handy! From my reading it seems the N20 engine is the more reliable, which leaves me with 18i/20i/28i as options, I think.
Presumably a remap would invalidate warranty/push up premiums? I am a total noob regarding mods of this level.
Budget-wise, I can stretch up to £14k or so.

[Argyll Andy]

it seems the N20 engine is the more reliable,

I would say the opposite, the N52 in the 23i and 30i is pretty much bulletproof if we’ll maintained. That’s NOT saying the N20 is unreliable, but there CAN be issues with timing chains as an updated kit is in the later cars.

I agree with Pnndrew, (which as a rule we try not to do) that the 20i may be better for a daily run around for fuel etc.If so there’s a lovely Valencia Orange one for sale on here but I’m not sure if it has a ski hatch

viewtopic.php?t=136419

[Ole gits rule]

Just watch for SE Highline spec cars advertised incorrectly, they have Msport seats but no iDrive so can be seen easily.

I reckon 90% of the Highline specs advertised on Autotrader, etc have exactly this problem especially from dealers.

100% agree and it drives me mad - its almost as if they retrying to sell someone who knows no different a higher spec car and normally at the Msport price


From a fuel cost point of view, over 4000 miles using the average MPG of the 23i 4pot vs the 30i 6pot, there's about £250 difference based on today's super-unleaded price. That's fuel alone and doesn't take into account reliability of the engine. Any stats for maintenance costs would be handy! From my reading it seems the N20 engine is the more reliable, which leaves me with 18i/20/i/23i/28i as options, I think.
Presumably a remap would invalidate warranty/push up premiums? I am a total noob regarding mods of this level.
Budget-wise, I can stretch up to £14k or so.
[/quote]

Firstly, the 23i is a six pot, the 18i/20i & 28i are the 4 pots - I believe both engines are fairly reliable if looked after correctly although as Andy said there are know issues on the timing chain but not certain how often that appears.

My 23i if driven sensibly can achieve in excess of 40mpg on a run quite easily, push the loud pedal and it will drop to low/mid 30's

As always said on here buy a 18i or 20i and have it remapped as you will have more choice and save a few quid when buying the car

Remap, unless you buy from a BMW dealer with an approved warranty then most dealers only offer 3 to 6 months so nothing to worry about on that front and quite a few on here don't seem to have mush trouble insuring a car with a remap or see ny significant increase in premium.

[Ole gits rule]

it seems the N20 engine is the more reliable,

I would say the opposite, the N52 in the 23i and 30i is pretty much bulletproof if we’ll maintained. That’s NOT saying the N20 is unreliable, but there CAN be issues with timing chains as an updated kit is in the later cars.

I agree with Pnndrew, (which as a rule we try not to do) that the 20i may be better for a daily run around for fuel etc.If so there’s a lovely Valencia Orange one for sale on here but I’m not sure if it has a ski hatch

viewtopic.php?t=136419

That is an absolute belter - best colour and decent spec

[Pondrew]

18i/20i/28i are the N20 4 pot twin scroll turbo. All exactly the same engine with different maps from the factory.

23i and 30i are N52 normally aspirated 6 pot, 2.5 and 3 litre respectively.

35i and 35is are N54 twin turbo (two separate turbos not twin scroll) 6 pot.

In real world driving you won't get an average 30mpg out of any of the 6 cylinders.
N52 you may be able to nudge it if you drive carefully (but then what's the point), N54 you will get average of 25-28 and less if you drive like a loon.
N20 (whichever power you have) you will get 35 plus (ours averages 37 on A roads and town mix and my wife has a heavy right foot).

For up to £14k, you should be able to find a really good car with whichever engine you decide (you will struggle to find a good 35i for that though).

If you are looking at the N20, remapping has been discussed thousands of times on here. It will void any warranty (depending on the warranty) but isn't expensive to insure and makes a world of difference to the 18i and 20i.

Problem with forums, if you ask for advice you will get 200 different answers with people trying to persuade you from their experiences. All for the right reasons, as people are really helpful. It can be more confusing, though!

[Zed Baron]

Hi, the 23i is a 6 cylinder car (almost the same as the 30i) naturally aspirated with no turbo. I've had one for the last 8 years as a weekend car and its been brilliant, very reliable and economical to own. If you are planning to use your new car as a daily, then maybe the 2.0 variants maybe preferable. Slightly better fuel economy and lower RFL, can't comment on remapping as I've never been interested in breaking the sound barrier but I would ensure that any potential car has a good service history, depending on mileage... timing chain etc. Make sure the car you choose has the extras, BMW charge for everything and some are easy to retrofit and some are impossible or near impossible depending on skill and equipment. These cars are getting on now but they still look good.

[Pondrew]

I agree with Pnndrew, (which as a rule we try not to do)

He giveth with one hand and taketh away with the other.
And spell my name correctly, please. I don't call you "Argyll Audrey".

OP; ignore them. They all love me really. It's just jealousy as I'm so 'windswept and interesting'.

[Argyll Andy]

They all love me really. It's just jealousy as I'm so 'windswept and interesting

You know I do,…….. maybe not the first description that came to mind but it’ll do

And spell my name correctly, please. I don't call you "Argyll Audrey

I’m multi tasking if you call me Audrey that’ll be one of the better things I’ve been called, and that’s just this morning

[Jellybaby38]

Have made an edit on the fuel calculation - it was indeed done with the 20i and not the 23i - I was multi-tasking and may have been looking at cars at the same time I have been paying attention, honest!

[Jellybaby38]

For those of you with experience of the N20, approx what mileage does the timing chain become a problem?