Just how indicative are things like the JDPowers (or whatever they're called) surveys?

Clem_Dye

Distinguished Member
My wife and I recently traded-in our diesel BMW X1 (about 3.5 y old) for a new Suzuki Vitara S. The deal was good (for a number of reasons). According to the JDP survey that I saw, BMW was 28th out of 34, whilst Suzuki was 2nd in terms of reliability. However, those results just don't square with our experiences.

Our BMW had two faults in 3.5y -- the driver's seatbelt got a bit shredded on my wife's coat and needed replacing, and the front screen washer system needed a flush-out. Contrast that with our new Suzuki. Within a week of having it, the driver's door started rattling and needed attention. Yesterday, the reversing camera worked loose, and the car will need to go in again to be looked at. Two faults in less than two months of ownership, as opposed to two faults in the 3.5y we had the BMW.

Part of the reason for going for the Suzuki was its supposedly better reliability than most of the cars in the survey. Our experiences don't seem to match the results. In both cases, the faults are minor, but just like things like hi-fi magazine reviews, I wonder just how much store you can place on these types of surveys?


Clem
 
I don't pay much attention to it at all. Having a decent warranty is much more important when you buy new.

Also surveys like that demonstrate how they were rated in the past. It doesn't say anything about today and the future.
 

lovegroova

Well-known Member
An understanding of statistics and probability is the most important thing to think about when looking at these surveys.

The best cars have "no fault" rates of about 95%, the worst around 75%. Either way, you might get a fault with a particular car, but the chances are lower with some than with others.

A sample of one of each car is no measure of brand reliability.

You just got unlucky.

A decent warranty is all very well, but the hassle of returning a new car to a dealer to have it fixed is a pain.
 

EndlessWaves

Distinguished Member
They're probably pretty good indicators about how happy people who are likely to buy a certain car are with it.

For things like objective reliability numbers they're likely pretty poor.

Unfortunately most sources don't publish their statistical methods, which makes it very hard to say whether they're any good or not.
 

gibbsy

Moderator
One of the strange things about these surveys is when people moan about practicality. That was one of biggest 'faults' with the VW Scirocco, it is not practical. Didn't these dimwits work that one out before they bought it! Were they really that surprised when their six foot rear seat passenger had to go to an osteopath after a short trip. Bunch of Richard Craniums.
 
One of the strange things about these surveys is when people moan about practicality. That was one of biggest 'faults' with the VW Scirocco, it is not practical. Didn't these dimwits work that one out before they bought it! Were they really that surprised when their six foot rear seat passenger had to go to an osteopath after a short trip. Bunch of Richard Craniums.
Fully agree. Totally invalidates these kind of surveys. Very similar with many online reviews and feedback mechanisms. A Chinese I ordered food from on just eat got a one star review only comment there was that it was 10 minutes late. Seriously? Some people are just too stupid to be allowed to provide feedback.
 
The JD Power surveys are a great example of bad statistical method. The respondents are self-selecting, which means that they are not representative of the population as a whole. Data is entered as, if I remember correctly, a one to five rating, i.e. in 20% increments. . . the results are then expressed to two decimal places! Then there's the "forum factor" - threads on fora (Alfaowner, I'm looking at you!) exhorting owners to give positive responses to such surveys to make their cars look good. Add to this the subjective nature of some of the categories & you have a document which is, by any objective standards, meaningless.
 

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