Z4 M Pistonheads Price Index - Week 10 - Updated

Z

ZermattV

Elite
 Aberdeenshire
After the M price post thought it might be worth keeping track on here - I plan to do this every couple of weeks to keep track of prices - totally unscientific but might be some fun

the Method - Calculate Average Roadster Price of the Asking Price on Pistonheads and average the associated Mileage do the same for Coupes and divide the coupe price by the roadster price to work out the Coupe factor and also supply the delta.

pistonheads used for ease of searching cars in the wrong category, POA and offers for purchase all ignored. Supposed to spark debate and banter this is not Glass's .


So here goes:

Week 8 2014 -

Roadster 9 Cars Avge Asking Price 13995 Avge Mileage 42120
Coupe 10 Cars Avge Asking Price 18231 Avge Mileage 37262


Week 12 2014

Roadster 7 Cars Avge Asking Price 14328 Avge Mileage 34500 - Med price 13000 Med Miles 37000
Coupe 16 Cars Avge Asking Price 18379.5 Avge Mileage 37831- Med Price 18497.5 Med Miles 33375



week 8 Coupe Tax 4236 pounds Week 8 Coupe Factor 1.3 - yep that's right a whopping 30% !!!

Week 12 Coupe Tax 4051.56 Week 12 Coupe Factor 1.28 on the average almost 5.5k on the mean


Week 19 2014

Roadster 11 Cars Avge Asking Price 15775 Avge Mileage 44228 - Med price 15000 Med Miles 47000
Coupe 18 Cars Avge Asking Price 18231 Avge Mileage 48425- Med Price 18495 Med Miles 51406

Week 19 Coupe Tax 2174 Week 19 Coupe Factor 1.14 ....... Those Roadsters are coming back

Week 4 2015

Roadster 9Cars Avge Asking Price 14481 Avge Mileage 50831.3 - Med price 14995 Med Miles 44900
Coupe 12 Cars Avge Asking Price 18432 Avge Mileage 44223- Med Price 16995 Med Miles 51000

Week 10 2015

Roadster 7 Cars Avge Asking Price 18156 Avge Mileage 45738.7 - Med price 16950 4 Med Miles 44900
Coupe 13 Cars Avge Asking Price 19863 Avge Mileage 47175- Med Price 18850 Med Miles 47343
 
Don't forget to factor in the 10% average mileage difference between the roadster & coupe - so the coupe is in fact only about 27% more expensive :poke:
 
I like it, will be fun to see. What about also dividing asking price by mileage to get price / mile?

Could be interesting to see how it develops / whether any trends appear.
 
StevenH72 said:
I like it, will be fun to see. What about also dividing asking price by mileage to get price / mile?

Could be interesting to see how it develops / whether any trends appear.
Click to expand...


Good idea - been thinking on similar- I don't think a 42k vs 37k difference would sway prices too much. I've decided to add any price even the 25k coupe as there is likely to be similar Roadsters .
 
ZermattV said:
StevenH72 said:
I like it, will be fun to see. What about also dividing asking price by mileage to get price / mile?

Could be interesting to see how it develops / whether any trends appear.
Click to expand...


Good idea - been thinking on similar- I don't think a 42k vs 37k difference would sway prices too much. I've decided to add any price even the 25k coupe as there is likely to be similar Roadsters .
Click to expand...

Sure it makes sense, it would be impossible to account for spec differences, private/trade, condition, service intervals etc. We'll just assume that over the long run these variances will even themselves out.

Yeh I don't think it will sway prices much, but it could do in the future (i.e. if one week the coupés average 35k and roadsters 16k, unlikely I know, but still), adding the "£/mile" figure could just be a nice standardisation. top thread though, will be watching with interest! :thumbsup:
 
This is the £/mile for the first week's data:

Roadster = £0.33/mile
Coupé = £0.49/mile

Coupés are 148%, so a 48% coupé tax :o
 
Cheers Steven - pondered exactly the same and as the build numbers were broadly similar I think the differences in spec should even themselves out - it will get swayed as the numbers of cars is only going to be 10-15 each time so one odd price will swing it .

And we could get odd weeks as you say.... We may be able to keep track it might just be a lot of rubbish ... But it occupied me on the Train this evening!
 
ZermattV said:
Cheers Steven - pondered exactly the same and as the build numbers were broadly similar I think the differences in spec should even themselves out - it will get swayed as the numbers of cars is only going to be 10-15 each time so one odd price will swing it .

And we could get odd weeks as you say.... We may be able to keep track it might just be a lot of rubbish ... But it occupied me on the Train this evening!
Click to expand...

Yeh you're right, but I think it will give some indication. Over the long run, if the prices are mapped into some sort of graph at the end of the year I'd think that you'll be able to see some kind of trend
 
And for fun only ....

this Weeks Average Roadster

http://www.pistonheads.com/classifieds/used-cars/bmw/z4m-roadster/bmw-z-series-z4-m-roadster--43k-miles/1987172?isexperiment=true

This Weeks Average Coupe

http://www.pistonheads.com/classifieds/used-cars/bmw/z4m-coupe/bmw-z-series-z4-m-coupe--one-private-owner-14-month-bmw-warranty-2006/1774340?isexperiment=true

Based on closest in price
 
Sorry, if you're going to do something like this you shouldn't really use the arithmetic average as it gets skewed too easily by outliers in the data set - keeping the maths simple, you'd get a better representation if you used the median value instead

For (a really simple) example if you had 5 values of 13, 14, 15, 16 and 50 an arithmetic average would give you an answer of 21.6 which is no real use as an indicator as it's skewed too high by the outlier value of 50

A median value of the same data set would give 15 which is obviously much more representative of the data on offer
 
I thought we'd get in a Median discussion - 13495 on the roadster 18495 on the Coupe - Coupe Tax 5k !!!

Mileages roadster median 43 166 versus average 42120?

I'll keep a check but there doesn't seem to be too many outlier values - you get some at mid 20s but none out in the 50s .
 
ZermattV said:
I'll keep a check but there doesn't seem to be too many outlier values - you get some at mid 20s but none out in the 50s .
Click to expand...
I wasn't seriously suggesting that there was a £50k car, it was just an exaggerated example to show how an outlier can skew a data set - the sort of thing that used to get drummed into us during stats lectures, along with gems such as 'absence of evidence is not evidence of absence' :roll:
 
I know you weren't expecting a car to be 50k - not even a Coupe. I'll keep a check on it :thumbsup:

It's early days but the 2-3k Coupe tax seems to be an underestimate lets see what summer brings
 
Asking price is not the same as selling price, will be interesting to see seasonality.
 
Well unless Roadster sellers are more realistic than Coupe owners, then the Coupe Tax would still apply regardless of the use of asking rather than selling price wouldn't it?
 
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