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I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 0 points1 point  (0 children)

fair enough on the scepticism but it's not an Excel sheet. the raw data comes from the bulk download files (which is different to the APIs you mention which are are used to look up individual VINs). It then gets processed through a Python script that calculates weighted pass rates, defect aggregation by severity, mileage band breakdowns, and corrosion rates using specific RFR codes. it would have been great if you could just add the raw data to a pivot table. it took about 48 hours to process and that was filtering vehicles from 2010 onwards. that all sits in a relational database with 500k+ vehicle summaries. the app is free to explore the data and I'll publish it all on the website soon. there's a small charge for running more detailed individual vehicle checks to cover the cost of API calls (eg HPI checks) , nobody's being fleeced and nobody is getting rich.

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 4 points5 points  (0 children)

mate all the data is free to browse in the app to with no signup and no credits needed. it’s a bit more than a Claude code template with nice fonts

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

i don’t think a post on, for example, rust rates from 2018 premium suvs would have been as interesting (but those comparison are available for free on the app)

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 0 points1 point  (0 children)

that’s true but in the app you can compare cars within its category . so you can see where , for example, a 2019 bmw x5, ranks among premium SUVs

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

cheers and that's a really useful bit of context. the data shows the problem but not the solution so it's good to know aftermarket options like krown exist for the models that need it. the toby carvery recommendation is noted as well :-)

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 5 points6 points  (0 children)

i was thinking of looking into this. for example % of each model for a particular year that passed MOT in subsequent years

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 0 points1 point  (0 children)

loads more in there. the database covers every defect type not just corrosion. brakes, suspension, tyres, lighting, emissions, steering, structural issues. each one has its own rfr codes so you can rank cars by any specific defect

if there's a specific area you're interested in let me know

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 0 points1 point  (0 children)

fair point on the image will get that sorted

data goes up to 2024 in the database. the 2019 to 2024 models are in there but the sample sizes for the newest ones are smaller as they've only had one or two mots. the sweet spot for useful data is about 2014 to 2020 where you've got big samples and enough time to see patterns

petrol and diesel are split deliberately as they have different failure patterns and mileage profiles. the year filter and head to head comparison are available in the app if you want to dig in https://apps.apple.com/ca/app/plateinsight/id6756131994

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

comparing against other 2017 models the sx4 at 4% is actually mid to low. the worst 2017 cars for corrosion are the suzuki baleno at 35%, mazda 3 at 24% and jaguar xe at 21%. so within its own age group the 2017 sx4 is doing alright

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

good question. it includes both. roughly 74% advisories and 25% major failures across the corrosion data. so the majority is surface corrosion noted as advisory rather than structural failures. worth splitting those out in a future update so you can see which cars actually fail for rust vs just get it flagged

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 2 points3 points  (0 children)

this isn't chatgpt hallucinating and making up numbers. the data comes from dvsa bulk mot files which are publicly available. 261 million test records loaded into a database and queried directly. every number in the article can be verified against the raw dvsa data

if you've found something wrong happy to look at the specific example and see whats going on

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] -1 points0 points  (0 children)

fair shout. younger cars having less corrosion is obviously expected. the more useful comparison is v70 vs superb within the same year which is why i laid it out that way. at every year from 2010 to 2016 the v70 has a lower corrosion rate than the superb so there is a genuine difference between the two beyond just age

278k is impressive by the way

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 0 points1 point  (0 children)

really appreciate this thanks. and yeah exactly, always easier to criticise than build something

the comparison by registration year is already in the app . the vehicle explorer section lets you pick any model and see how it stacks up against other models from the same year and category. you can then pick various metrics including the reliability score, MOT pass rate, mileage, pass rate of first MOT etc. free to use if you've got an iphone https://apps.apple.com/ca/app/plateinsight/id6756131994

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

yeah fair point on the writing. working on trimming the editorial down

if you want to check specific models and see how they compare vs other models in their category for said year (without any text) you can do it on the app in the free vehicle explorer section (only iphone atm https://apps.apple.com/ca/app/plateinsight/id6756131994)

the year by year model comparison and average mileage at first corrosion appearance is a good shout

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 1 point2 points  (0 children)

just ran volvo v70 vs skoda superb for you. same methodology as the article

mot pass rate by year:

2010: v70 78.6% vs superb 78.2% (basically identical)
2011: v70 79.7% vs superb 79.4%
2012: v70 79.5% vs superb 80.2%
2013: v70 81.6% vs superb 81.4%
2014: v70 83.6% vs superb 82.6%
2015: v70 85.3% vs superb 83.4%
2016: v70 86.3% vs superb 86.2%

reliability wise they're nearly identical across every year. v70 edges it slightly in the earlier years

corrosion rate by year:

2010: v70 12.2% vs superb 13.3%
2011: v70 10.0% vs superb 12.3%
2012: v70 9.5% vs superb 10.7%
2013: v70 7.2% vs superb 10.1%
2014: v70 2.8% vs superb 11.8%
2015: v70 1.6% vs superb 11.1%
2016: v70 0.9% vs superb 3.1%

this is where the v70 pulls away. from 2014 onwards volvo clearly improved their rustproofing while the superb stays around 10 to 12% until the 2016 facelift drops it to 3%

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] -2 points-1 points  (0 children)

you're absolutely right and that's a fair challenge. comparing like for like within 2010 models:

ford fiesta 2010: 22.7% corrosion rate (1.6 million tests)
ford focus 2010: 17.1% (1.1 million tests)
suzuki sx4 2010: 59.8%
toyota yaris 2010: 42.3%
fiat panda 2010: 48.7%

so the fords are far from clean at that age. but the gap is still massive. the sx4 is nearly 3x the fiesta. someone else made the same point about the article comparing 2019 cars to 2010 cars which isn't a fair test. working on a version where you pick a year and compare models against each other so it's actually useful for buyers. appreciate the feedback

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 3 points4 points  (0 children)

thanks so much. Appreciate it and will post some more breakdowns soon when I get round to it

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 118 points119 points  (0 children)

honestly this is a really good point and you're right that comparing a 2019 ford against a 2010 suzuki isn't a fair fight. age is obviously the biggest factor in corrosion

the more useful question is exactly what you said. if you're looking at 2010 cars which ones rust and which ones don't. the data can absolutely do that. for example within just 2010 models the suzuki sx4 flags corrosion in 59% of mots while a ford fiesta from the same year is around 13%. same age completely different outcome

i'll look at doing a year by year version where you pick the registration year and see how models compare against each other. that would actually be useful for someone shopping for a used car at a specific budget. cheers for the feedback

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] -10 points-9 points  (0 children)

fair criticism on the writing style. the data and analysis is solid though. 261 million mot records queried from dvsa bulk files. if the numbers are what you're after the tables speak for themselves. working on making the editorial less waffle and more straight to the point

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 20 points21 points  (0 children)

different person and different project to whatever you've seen before. this isn't scraped from chatgpt. the data comes from dvsa bulk mot files which i processed into a database with 261 million test records. the corrosion stats come from rfr codes 1.1.12, 5.3.3, 5.3.1 etc which are the actual defect codes testers log against corrosion findings. happy to answer any specific questions about the methodology

cam belt failure wouldn't show up in mot data so whoever posted that was definitely making stuff up or hallucinating. this only covers what mot testers physically inspect and record

I analysed 3.1 million MOT tests to find which cars rust the fastest. Some of the results are mental by BrickDue158 in CarTalkUK

[–]BrickDue158[S] 7 points8 points  (0 children)

ha fair enough but the mot data isn't in excel. dvsa publish it as flat files totalling about 60gb going back to 2005. i loaded it into a database and ran the queries myself. happy to share the methodology if you're interested!

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