Government is rubbish. They'll go the easy lazy route so id say date of registration as in, Registered after 1st January 2001.
Printed on the V5 are our Co2 readings, I'll guess that was provided by BMW at point of mass production.
I assume if thats maintained that reading you're ok...until they decide its too high for modern life in the UK
Again, they'll pile the onus on the MOT garage with a big wooden stick hanging over them full of ' conform or be removed from MOT testing' wrote on it...
Or am I getting old a cynical
No, I expect that's how they'll do it.
Instead of the MOT station just saying it's a PASS, the actual readings will be uploaded to DVLA. The data has been available for a long time. What hasn't been there is the computer capability to interogate it on a mass scale. It is now.
I used to work in data analysis. In 2003, an MS Access database was limited to 2Gb maximum, but started to fall over at 500Mb. I dread to think what the limit is now.
We were interrogating tables of a couple of 100,000 lines with probably twenty to fifty columns, some were text fields (the worst). You could have a lunch break if you did a "contains query" with multiple arguments.
Think of searching the police database for all Caucasians with blue eyes, over 1.80m tall whose name has the letter P, G and K in it.
Now, the same query is on the screen as soon as you hit the ENTER key.
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I can see problems if a manufacturer brings out a new, cleaner, model before all the previous models have been registered.
For instance, imagine the S50 M Roadster were 350g/km and the S54 M Roadster were 300g/kg
In 2000, both were being registered and sold. Some S54s would have been registered in January 2000 and some S50s would also have been registered in January, but probably sold at a discount, as they were last year's model.
If the S54 emissions is recorded on the DVLA database for BMW M Roadsters registered in January 2000, then all S50s will fail the new test. There is a get-outta-jail clause in the link, but I imagine it will be a PITA trying to use it.
At the end of the day, it won't affect me - not for my BMWs, anyway.