Hi folks, new member looking for some buying advice. I've been looking at moving into a Z4 as my MX-5 project has become a long term thing. I've been to look at a few , a 2007 2.5Si, a 2006 2l and a 2005 3l. I've been reading a few bits and the general advice seems to be buy on condition. All 3 seemed to drive ok, the 2l had an exhaust blow though and it was more condition or suspect things that put me off. I've ideally settled on a 2.5Si or 3l, if I can find one. I may be going to look at a 2006 2.5 non Si that looks tidy though. I guess my question at the moment is what are the engines like with mileage on them? Is a car in tidy condition body and interior with higher mileage a worthwhile choice?
Buying advice
- Thread starter Enigmatik
- Start date
North West Surrey
Hi and welcome to the forum. 
Personally I'd stick to the straight 6s as that's one of the Z4s unique features, plus they sound better and from what I have read the 4 cylinder engines seem to have more issues.
There was a facelift in early 2006 when the M54 6 cylinder got replaced by the newer N52 engine. The pre-facelift 2.5i was rated at 192PS and the 3.0i at 231PS. Facelift 2.5Si was 218PS and the 3.0Si was 265PS - but the facelift 2.5i is only 177PS so may be one to avoid! Especially as running costs are the same whichever size engine they have.
Both engines seem capable of covering high mileages without major issues. I had an E46 with the M54 that drove just fine when I sold it on 103K miles and an E91 with the N52 2.5Si engine that was running great after 139K miles. Likewise my second 3.0Si was running strongly when I sold it on 91K and my current E90 with the 3 litre N52 has done 115K and still runs really sweet.
So you're probably right to focus on condition and history, plus possibly spec if there are some options that you "must have".
Enjoy the search anyway.
Personally I'd stick to the straight 6s as that's one of the Z4s unique features, plus they sound better and from what I have read the 4 cylinder engines seem to have more issues.
There was a facelift in early 2006 when the M54 6 cylinder got replaced by the newer N52 engine. The pre-facelift 2.5i was rated at 192PS and the 3.0i at 231PS. Facelift 2.5Si was 218PS and the 3.0Si was 265PS - but the facelift 2.5i is only 177PS so may be one to avoid! Especially as running costs are the same whichever size engine they have.
Both engines seem capable of covering high mileages without major issues. I had an E46 with the M54 that drove just fine when I sold it on 103K miles and an E91 with the N52 2.5Si engine that was running great after 139K miles. Likewise my second 3.0Si was running strongly when I sold it on 91K and my current E90 with the 3 litre N52 has done 115K and still runs really sweet.
So you're probably right to focus on condition and history, plus possibly spec if there are some options that you "must have".
Enjoy the search anyway.
Hi Mr Tidy thanks for the advice. Is there anyhting that would put you off a car with 120k+ miles or anything in particular to look for at that mileage? I've seen all the stuff about coolant tank leaks, water pumps on the later engines, etc. Seems to be a few with failed aircon, which isn't major but is a seized compressor something to watch for?
I wouldn't be put off by 120K miles on any 6 cylinder BMW if everything else checks out OK.
As you say cooling systems can have issues with bowed radiators and split expansion tanks, and the electric water pumps on the N52 engine can just die. I've had 4 cars with N52s and needed new pumps on 2 of them, one at 60K miles, the other at 135K! The main issue is they just stop pumping so the engine overheats in about a mile, and new OE pumps cost £250 or so (or £500 from BMW).
But once it's replaced it should work for years.
On E85s look out for roof motor issues. BMW located them below the roof drains so they can drown, but there are a few people on here who can often revive them and it's worth getting them relocated to the boot for £200 or so - much cheaper than a new motor!
And rear brake pipes can corrode in front of the passenger side rear wheel.
Both engines can suffer from oil leaks from the cam-cover gasket and the oil filter housing gasket so it's worth checking for any signs of leaks and both are prone to using a bit of oil but that isn't really an issue so long as you keep on top of it. FWIW the N52 engine has no dipstick, you check it by pressing a button on the dash.
I don't know of A/C compressor issues. I've only had AC problems with 3 of my 8 BMWs, first one (E46) just needed a regas, next one (E86 No.2) needed a new condensor as they can get hit by stones and latest (current MC) just needed a regas.
As you say cooling systems can have issues with bowed radiators and split expansion tanks, and the electric water pumps on the N52 engine can just die. I've had 4 cars with N52s and needed new pumps on 2 of them, one at 60K miles, the other at 135K! The main issue is they just stop pumping so the engine overheats in about a mile, and new OE pumps cost £250 or so (or £500 from BMW).
But once it's replaced it should work for years. On E85s look out for roof motor issues. BMW located them below the roof drains so they can drown, but there are a few people on here who can often revive them and it's worth getting them relocated to the boot for £200 or so - much cheaper than a new motor!
And rear brake pipes can corrode in front of the passenger side rear wheel.
Both engines can suffer from oil leaks from the cam-cover gasket and the oil filter housing gasket so it's worth checking for any signs of leaks and both are prone to using a bit of oil but that isn't really an issue so long as you keep on top of it. FWIW the N52 engine has no dipstick, you check it by pressing a button on the dash.
I don't know of A/C compressor issues. I've only had AC problems with 3 of my 8 BMWs, first one (E46) just needed a regas, next one (E86 No.2) needed a new condensor as they can get hit by stones and latest (current MC) just needed a regas.
I would go for the 2.5, mine is a 2003 pre facelift, it had 93k on the clock when I got it, few marks around it but nothing major and an interesting leather interior, was retrimmed at some point in its life. Engine sounded ok and pulls like a train, had to replace the starter motor when that died. Put 18inch wheels on it with new tyres, larger size on the rears. Changed all the fluids and plugs so I knew what was in it from the start of my ownership. First MOT in my ownership was a Pass with an advisory for rear nearside brake pipe corroded. Sorted that by fitting stainless braided hoses all around, using them on the rears got rid of the middle section of hard line on the oem hose. Also cleaned up the hard lines that emerge from the plastic channel under the car into the nearside wheel arch and gave them a coat of paint. Replaced the CCV system as preventative maintenance, fitted after market heated seat pads and moved the roof motor into the boot as preventative maintenance. General tinkering saw the wiper motor opened up and the grease cleaned from the electrical contact plate inside that migrates across it from the worm drive and messes up the wipers parking position. Had to replace a brake pressure sensor on the master cylinder the other day after I got warning lights lit up for Traction Control and an amber handbrake light. New sensor and code cleared using a Creator 310+ code reader.
Uses a drop of oil but it has a dip stick so regular checks are easy enough over the models that don't have dip sticks.
Loads of these cars out there you should find what you want easy enough.
Uses a drop of oil but it has a dip stick so regular checks are easy enough over the models that don't have dip sticks.
Loads of these cars out there you should find what you want easy enough.
Mr Tidy, do you think it's worth buying and fitting a water pump on a N52 at purchase for peace of mind? I understand the pump itself is expensive but the fitting videos seem fairly straight forward.
Hi Colb, The 2.5 I'm going to look at is the 177bhp model so bit down on the earlier and 2.5Si I've seen. I'll see if I can live with less power if everything else seems ok, though did read some stuff about changing the manifold to the same as the Si and a remap getting you nearer the same power. It sounds like you do a lot of the small stuff yourself which is reassuring as only like paying a garage if it's a major thing or there is a rush/it will be a pain factor. Is the Creator 310+ a recommended reader for these?
Hi Colb, The 2.5 I'm going to look at is the 177bhp model so bit down on the earlier and 2.5Si I've seen. I'll see if I can live with less power if everything else seems ok, though did read some stuff about changing the manifold to the same as the Si and a remap getting you nearer the same power. It sounds like you do a lot of the small stuff yourself which is reassuring as only like paying a garage if it's a major thing or there is a rush/it will be a pain factor. Is the Creator 310+ a recommended reader for these?
Creator 310+ is definitely worthwhile the money. I have one myself an am fully satisfied with it.
As for the engine choices: I am fully with Mr. Tidy; nothing beats a straight six. My brother owned an ‘07 2.0i E85 which, well, functioned, but lacked the rewarding engine sound of the straight sixes. I would not recommend that engine.
(Following some Mx-5s) my Z4 career with an ‘07 2.5si E85. Traded that in on a ‘03 3.0i E85, which since about 1.5 years is accompanied by an ‘08 3.0si E86.
N52 2.5si is a lovely engine, which if you treat her nicely purrs to you. Be aware though that the N52 2.5si can suffer from very serious engine trouble. Chances are pretty low, but if that engine starts acting up, it really can be serious. Not just very heavy oil consumption.That does not apply (to the same extent) to the n52 3.0si. The 3.0si also has a lot more “umpfff” compared to the 2.5si.
The M54 3.0 (as well as the M54 2.5i) also can suffer from oil consumption, however there are not much other known engine issues with it. It burbles less than the N52 si engines, but is a very, very pleasant engine to drive.
If it were me, I would test drive the 3.0i and the 3.0si and then make a decision.
As for the engine choices: I am fully with Mr. Tidy; nothing beats a straight six. My brother owned an ‘07 2.0i E85 which, well, functioned, but lacked the rewarding engine sound of the straight sixes. I would not recommend that engine.
(Following some Mx-5s) my Z4 career with an ‘07 2.5si E85. Traded that in on a ‘03 3.0i E85, which since about 1.5 years is accompanied by an ‘08 3.0si E86.
N52 2.5si is a lovely engine, which if you treat her nicely purrs to you. Be aware though that the N52 2.5si can suffer from very serious engine trouble. Chances are pretty low, but if that engine starts acting up, it really can be serious. Not just very heavy oil consumption.That does not apply (to the same extent) to the n52 3.0si. The 3.0si also has a lot more “umpfff” compared to the 2.5si.
The M54 3.0 (as well as the M54 2.5i) also can suffer from oil consumption, however there are not much other known engine issues with it. It burbles less than the N52 si engines, but is a very, very pleasant engine to drive.
If it were me, I would test drive the 3.0i and the 3.0si and then make a decision.
Hi Mau, I'll take a look at the scanners. Going to look at a 177bhp 2.5 today, not first choice but looks tidier and less suspect than the 2.5Si and 3l I went to see. I've now been in 4cyl and 6cyl models so 6cyl it is. Unfortunately only 3l Si I've seen is about 2.5 hrs drive in Blackpool. Choices in Scotland seem limited. If this one isn't right I'll need to plan a raid down south I think.
I had a 2.5i which had a custom stainless steel exhaust, and although it may not have been as powerful as the 3.0 or so it never failed to put a smile on my face, it sounded great (but not on a motorway) 
As others have said, history and condition were key for me.
I was originally looking for a 20k mile M but ended up with one at 46k due to the history and condition of it.
Good luck with your hunt
As others have said, history and condition were key for me.
I was originally looking for a 20k mile M but ended up with one at 46k due to the history and condition of it.
Good luck with your hunt
It seemed a lot more honest than the others i've seen, not perfect but price is making it tempting.
Pro's
M-Sport seats but no heating or electrics
Receipt for Water Pump in 2019 which was only 6k miles or so
It's pretty presentable but needs a really good clean, not had a lot of use
Didn't see any major oil leaks or other leaks
Drove nicely
Has a weird dash mounted button with a R and like a chequered flag on it with different modes? Think it does what the sport button does, changes throttle response etc, trying to google just now (Found it, RaceChip XLR Throttle response controller, looks like older model based on Google images)
Seems to have been lowered but not too firm
Con's
Front bumper needs painted/refitted
Little condensation on nearside front headlamp and it's a bit foggy/faded
Has after market wheels with 20 mil spacers and unknown brand tyres (but decent tread)
Needs to be a wheel/spacer imbalance. You can feel it patter over 65mph but don't feel it in the wheel?
Needs a good clean
Roof motor hasn't been moved but goes up and down quickly
Air con doesn't work
Rear view mirror milky at bottom, guy has spare but tried fitting it and central locking stopped working, so swapped it back.
Considering a cheeky offer on basis everything saved I can put into tidying it up.
Pro's
M-Sport seats but no heating or electrics
Receipt for Water Pump in 2019 which was only 6k miles or so
It's pretty presentable but needs a really good clean, not had a lot of use
Didn't see any major oil leaks or other leaks
Drove nicely
Has a weird dash mounted button with a R and like a chequered flag on it with different modes? Think it does what the sport button does, changes throttle response etc, trying to google just now (Found it, RaceChip XLR Throttle response controller, looks like older model based on Google images)
Seems to have been lowered but not too firm
Con's
Front bumper needs painted/refitted
Little condensation on nearside front headlamp and it's a bit foggy/faded
Has after market wheels with 20 mil spacers and unknown brand tyres (but decent tread)
Needs to be a wheel/spacer imbalance. You can feel it patter over 65mph but don't feel it in the wheel?
Needs a good clean
Roof motor hasn't been moved but goes up and down quickly
Air con doesn't work
Rear view mirror milky at bottom, guy has spare but tried fitting it and central locking stopped working, so swapped it back.
Considering a cheeky offer on basis everything saved I can put into tidying it up.
That's interesting.
M-Sport seats are a bonus even if they aren't heated or electric, a recent water pump and working roof motor are also good news.
Non-functioning AC would be a worry - my 2nd Z4 needed a new condensor which cost around £300 at an Indy. If it was just a regas the seller would have had it done!
Good luck anyway, whether you go for a cheeky offer or look elsewhere.
M-Sport seats are a bonus even if they aren't heated or electric, a recent water pump and working roof motor are also good news.
Non-functioning AC would be a worry - my 2nd Z4 needed a new condensor which cost around £300 at an Indy. If it was just a regas the seller would have had it done!
Good luck anyway, whether you go for a cheeky offer or look elsewhere.
Attleborough, Norfolk
Congrats but same as enuff - no image