Why do Z4s fair worse than 3 series for MOTs?

M

Magicarcher

Active member
 Warwickshire
I've been looking for a 3 series estate for my wife. One of the things i always do is look at the MOT history to see the sort of things a car fails on. It became apparent that the 3 series appears to suffer far fewer failure than a Z4 for equivalent age/mileage.

I decided to do a quick check. I went on autotrader and looked for cars between 10-12 years old with between 80k and 100k mileage. Looked for Z4s first then 3 series estates, petrol manuals. I looked into the MOT history for the top ten cars displaying registrations (sorted by price). Not an exhaustive comparison but gives an idea.

The Z4s performance:

Average failures = 3.6
Modal failures = 4
Highest number of failures = 6
Lowest number of failures = 1

The 3 series performance:

Average failures = 2.2
Modal failures = 2
Highest number of failures = 4
Lowest number of failures = 0

Would anyone like to speculate why the Z4 fairs so much worse than 3 series?
 
Zeds are probably driven a bit harder as people think they're proper sports cars (which they're not - they're fast GT cars). So stuff will wear quicker.
 
Your sample data is too small for any meaningful results. So you may or may not be correct.

It's good that you set a few meaning full parameters. However, I can't help thinking the cars are chalk and cheese, so what is the point of trying to compare them?

Your data is not allowing for type of use. Type of driver etc etc etc.......

Questions that might be more relevant.

Which zed4's fair best?

Do the preface lift cars fair better than the post face lift cars?

Is the steering system in the ///M more or less likely to fail than the one in the other E85/86 models?

Is the Zed4 more likely to fail an MoT than a similar Boxster?
 
Strange really, seeing as most of the E85/E86 architecture is the same as the E46. :?

But does the OPs sample include E9* 3 Series models as well?
 
It could also be due to people buying the roadster for a summer and not looking after it. Then selling it on.

They do get a hard life, but they also stand up to it too.
 
It would be interesting to see what they are failing on


3 series snap springs just as often as Z4's and any other bmw ..

I notice that brake pipes seem a common issue and crap handbrake performance, again though that seems right across the board with BMW

Badly worn tyres and condensated lights seem to be a failure point on the Zeds we see
 
I'd also add that rear tyres being illegal would attribute greatly to failures like the springs. Due to the camber they'll wear on the inside (becoming illegal) but if you're only looking at the wheel face on it'll seem like theres plenty of tred.
 
Well this thread fills me with confidence.... Z4 is in for MOT at 4pm!!

Fingers crossed I won't be adding to the failure statistics
 
Chris1981 said:
Well this thread fills me with confidence.... Z4 is in for MOT at 4pm!!

Fingers crossed I won't be adding to the failure statistics
Click to expand...

You should be ok, you will get a 3 series loaner if yours fails :rofl:
 
z4 went through with just 2 advisorys both for front brakes which is an easy fix! :thumbsup:

My old e46 went straight through too so I'd say that well maintained examples of either are fine for many years!
 
Why do Z4's fair worse than 3 series for MOT's? ........ Relax, fact is they don't according to VOSA (Dept of Transport) statistics available on the web.
https://good-garage-guide.honestjohn.co.uk/mot/bmw/z4/2008
https://good-garage-guide.honestjohn.co.uk/mot/bmw/3-series/2008

Apparently at 10 years old they both have a 74% pass rate which is better than average.

Failure reasons for 2008 Z4 are most likely for Springs, bushes, lamps and tyres, suspension being a particularly weak area compared to all other makes/models. Interestingly steering is 84% better pass rate compared to all other makes models.
9.8% fail on Suspension, specifically
4.4% fail on Coil springs
3.3% fail on Suspension arms (58% worse than other 2008 cars)
3.1% fail on Pins/bushes/ball joints (52% worse than other 2008 cars)
0.23% fail on Attachment (2 times worse than other 2008 cars)
1.0% fail on Shock absorbers
0.72% fail on Anti-roll bars (70% better than other 2008 cars)
0.72% fail on Front suspension joints
0.32% fail on Wheel bearings
0.045% fail on Trailing arms
0.045% fail on Radius arms
0.045% fail on Tie bars/rods
0.045% fail on Torque/reaction arms
0.045% fail on Macpherson strut

9.2% fail on Lamps, Reflectors and Electrical Equipment (46% better than other 2008 cars), specifically
2.5% fail on Headlamp aim (47% better than other 2008 cars)
2.5% fail on Registration plate lamp (44% better than other 2008 cars)
2.2% fail on Headlamps
1.9% fail on Headlamp (33% better than other 2008 cars)
0.23% fail on Headlamp defects which don't require an aim check on retest (2 times worse than other 2008 cars)
0.23% fail on Headlamp cleaning device (3 times worse than other 2008 cars)
0.045% fail on Headlamp defects which do require an aim check on retest
1.9% fail on Position lamps (56% better than other 2008 cars)
0.54% fail on Horn
0.41% fail on Stop lamp (89% better than other 2008 cars)
0.27% fail on Direction indicators (83% better than other 2008 cars)
0.14% fail on Rear fog lamp
0.090% fail on Hazard warning

0.045% fail on Battery

8.0% fail on Tyres
4.4% fail on Condition
3.8% fail on Tread depth
0.63% fail on Tyre pressure monitoring system (8 times worse than other 2008 cars)
0.090% fail on Size/type
0.045% fail on Valve stem
4.8% fail on Brakes (31% better than other 2008 cars)
2.1% fail on ABS (6 times worse than other 2008 cars)
1.4% fail on Hub components (52% better than other 2008 cars)
0.99% fail on Brake performance (67% better than other 2008 cars)
0.90% fail on Electronic stability system (5 times worse than other 2008 cars)
0.45% fail on Hydraulic systems (56% better than other 2008 cars)
0.23% fail on Parking brake

3.6% fail on Driver's view of the road (36% better than other 2008 cars)

1.5% fail on Exhaust, Fuel and Emissions (36% better than other 2008 cars)

0.72% fail on Road Wheels (110% worse than other 2008 cars)

0.63% fail on Registration plates and VIN

0.54% fail on Seat Belts and Supplementary Restraint Systems

0.23% fail on Steering (84% better than other 2008 cars)

0.090% fail on Body, Structure and General Items (84% better than other 2008 cars)
 
Mine has mostly always failed on suspension related.

It's so rock hard and rough when it's right or wrong that it can be wrong and you won't notice ;-)
 
dhobbs said:
It could also be due to people buying the roadster for a summer and not looking after it. Then selling it on.

They do get a hard life, but they also stand up to it too.
Click to expand...
+1 :thumbsup:
 
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