What Is My Car Worth? (Chart)
 

So I'm busy wasting time on a Sunday afternoon and I come across the Used Auto Graph site (Used Auto Graph) and create a chart of 986 prices. Unfortunately, the data between base and S models is not broken out separately.

After looking at the chart, I notice that many of the active listings (green and blue dots) are below the average selling curve. So I wonder, what is the active listing average pricing?

So I download the data set to Excel, filter only the active listings, and do a linear fit. This kind of provides a first order estimation of the average listing price of a 986 (based solely on mileage).

Not perfect, but interesting. What do you all think? (besides saying that I need to get a life).

Used Auto Graph Data
http://i1114.photobucket.com/albums/...ps713ae6f3.jpg

Active Listings
http://i1114.photobucket.com/albums/...ps36e455ab.jpg

I'd say your graph was spot one, but you need a pie chart to accompany it.

At a guess, I'd say the reason that the active listings are below the average curve is due to it being winter. You'd have to seasonally adjust (or graph it by season of sale) the prices to get rid of this artifact.

Otherwise, I like it quite a bit. Splitting it out by S and Base model would, as you say, be very informative, too.

Cheers,
Jason

I wonder if there is enough data to tease out the spread by substantive update periods as well. At the very least I expect the 2.5L 1997-1999 Boxsters would have a different resale value than a 2003-2004 Boxster (Base or S) even with the same milage.

I'm also curious about the 2.5L models specifically because of their potential reuse in Spec racing.

Ive watched boxster posts in the south east for the last three months and i think your graphs are spot on. i paid 15,700 for a boxster s with 33k miles on it.

Thanks for posting. Valuable info for both buyers & sellers.

Yes, the data is also available by model year. Here is the break out in two charts; early 97-99 and 2000-2004:

97-99
http://i1114.photobucket.com/albums/...ps7dc89b82.jpg

2000-2004
http://i1114.photobucket.com/albums/...ps2843f9d4.jpg

Who paid over $25k for the 97-99 with over 140k??????

I'd expect that would be one heavily modified 2.5l.

That should be a sticky post

The thing I don't get about those charts when it comes to high mileage Porsches is that some have extensive, major mainteance and upkeep performed, while others are just dumped into the market with little spent because the owner doesn't want to deal with it. Yet the pricing of either doesn't vary that widely. It makes it really not worth selling or investing in any Non-GT, water-cooled Prosche once out of warranty and over 50K miles.

And buying an air-cooled Porsche means you're constantly watching the odometer for fear of losing another grand in resale or fear of taking it out in anything but perfect driving weather.

One is disposable, the other is a baseball card with four wheels.
I guess the solution is to buy a Boxster and go racing.

Hah! Yes, there are some interesting "extreme" points in the chart that I'd love to know the details about. Unfortunately, links to the exact listings are not available.