Which BMW?

Peter Fenwick wrote: Don't worry, not going near a diesel!

Glad to hear it Sir!

Peter

The floorpan issue is one that goes back to the e36.  Where the rear subframe connects to the floorpan they can develop a tear in the floorpan.  My understanding is that the turning effect of the wheels/axle creates a stress/force that can rip the weld points on floorpan.  This was (is) a known e36 potential problem and more prevalent on the larger engined cars, presumably because the extra power/torque increases the twist effect.

There are weld points forward and rear of the axle on each side.  When the e46 came out the reinforced the forward weld points on either side.  My assumption is that this increases the stress on the rear points, or more specifically the nearside rear weld point (because of the main direction of turn/torque in the drive because on the e46 the failure point is almost always around the nearside rear subframe mount.  There are a couple of links attached to give you a sense of what its about, including one related to my sisters car.  This isn't an engineering answer so excuse the crudity of the explanation!

BMW have repaired a lot of cars, including my sisters, as goodwill gestures but I don't know if they are still doing it, my experience was a couple of years ago.  The proper repair involves basically striiping the rear end of the car, cutting out the centre of the floorpan and welding in a new section.  If you do a nose about on realoem you'll find that there is a specific part number for the replacement floorpan section (see part 1 on link below).  Between parts and labour there's a couple of grands work in it.  There are patch-it type fixes but not sure how effective.

BMW then updated the e46, in line with the introduction of the m54 engines in 2000 and reinforced the rear mount points too so there have been few issues on those.  When I was checking it out for my sister I did find that there were practically no other Tourings affected that I could find.  In her case it failed at about 6 1/2 years old with less that 60k miles.  The car was never abused and was more a family hold-all than a load lugger.

http://www.bavarian-board.co.uk/forum_posts.asp?TID=34492&am p;am p;am p;KW=floorpan

http://forum.e46fanatics.com/showthread.php?t=230988&hig hlight=subframe

http://forum.e46fanatics.com/showthread.php?p=5153753

http://www.realoem.com/bmw/showparts.do?model=AR52&mospi d=47670&btnr=41_1267&hg=41&fg=25

Re. the m54 engine.  My main concern about it isn't particularly the consumption but more about the long term effect of a car regularly running low on oil because people don't dip their cars too often.  My nikasil 523i still feels and runs like a new engine at 140k+.  Not too sure if a neglected M54 would feel or sound so good at similar miles. 

The 3.0 is a peach of an engine, really loved the power and delivery in my recently departed 330 but having driven my sisters 328i alongside the 330 its not too much of a poor relation unless you are really given it loads all the time.  In fact, her touring is a contender for replacing the 5 because I know the floorpan has been done and the M52 in these is pretty robust (overheating problems see to be the only real killer of them).

BTW. the other thing that I would personally avoid is any of the diesels.  Fab engines but there are too many stories of potential woe (swirl flaps, turbo's, fuel pumps, etc.) to make the extra few mpg worth the risk against potental bills of well in to 4 figures for the cheapest of these.

OK - by process of elimination....

M52 E46 - engines bulletproof, biggest concern would be the floorpan issue.  At this stage, because of cost of repair vs. value of car, an issue like that would turn a nice car in to a scrapper.  Eliminated.

M54 e46 - floorpan solved but the m54 likes a little drink of oil.  Eliminated.

M54 E39 - fairly bulletproof, except M54 prone to the same thirst as above.  Eliminated.

M52 e39 (dual Vanos, so 1999 or 2000) - by a process of elimination, the winner.  No fundamental engine concerns, body is fairly rust resistant, plenty of space, comfort and reasonable economy.  Best of all, the price point allows you to pay top money for the best car and still have plenty of change from your budget.  Little to choose between 520i, 523i or 528i in terms of economy or servicing, etc. so no reason not to have a 528i.

Been having the same debate myself contemplating a replacement for my e39.

Another thought has sprung to mind.

If you are looking to put a kiddie seat in the back of the car, have a think about ISOfix points.  Not sure what BMW models have them fitted but basically it is a locating lug that allows you to attach a kiddie seat directly to the chassis rather than using a seat belt.

The pre facelift E39s didn't have ISOfix in the rear, not sure about post facelift models.

The E46 might have them, her pal who has the E46 based Compact has ISOfix as standard and uses an ISOfix kiddie seat for carting around her sprog.

Ok.

Lets say you have £6k to spend.

Car must not be massively expensive to run, but must be reasonably fast. 25mpg+ and a budget of about £1600 a year to cover all running costs except fuel. It must also have a decent sized boot and preferably be a 4 door although a coupe is not out of the question as long as it has decent sized back seats.

My thoughts have been

E46 232/325/328/330

E39 528/530

A couple of more interesting thoughts have been

E36 M3 but i'm guessing running costs could be too high

E39 540 bad MPG but you can pick up a decent one for £4k which would leave change for an LPG conversion. Same for 740 but I expect servicing/parts would get silly.

Also any savings on purchase price can be hung onto to cover unexpected repairs, so it the car costs 4k then 2k in the bank to pay any big bills.

Any thoughts?