Free Traffic Legal Advice

ULEZ and CAZ work on same emission levels.
So a motor that is compliant in one should be in tother.
They use differing databases (dunno why) and both are or should be populated by same DVLA data.
But for whatever reason they can contradict.

Your 2005 Porsche is on the date when euro 4 came in and predates when newly registed had to be.

You can query here https://contact.drive-clean-air-zone.service.gov.uk/
You may need to get a conformity certificate from Porsche and may find that you are not actually compliant...which would muck up ULEZ as well

Don't miss deadline to challenge waiting for info.... I would be phoning Porsche customer services today.

As I read the VCA database the Boxster type 987 was introduced in May 2005 and all models are certified as Euro 4. Prior to the type 987 all Boxster models are certified as Euro 3.

It seems to me that the OP's Porsche is a Euro 3 spec as it was registered in March 2005 and predates the type 987. Those models might meet the Euro 4 standard but Porsche never had them certified as such. If the OP obtains the type approval cert from Porsche then it's likely to say Euro 3 and/or EC 2000. But worth checking anyway.

The inclusion of the Euro class on the V5c and presumably the DVLA record is a much newer innovation, came in around 2018 I think. So any request for information on an older car won't include the Euro class.

AIUI the ULEZ system will check for compliant NOx if no Euro status is available. The OP's car has complaint NOx. Seems Birmingham's system lacks such refinements.

1.—(1) A vehicle meets the standards set out in Tables 1 and 2 if—
(a) the vehicle is certified by the appropriate national approval authority as having been manufactured
to satisfy the EC emissions standard specified for that vehicle in column (e) of the Table;
(b) the vehicle has been retrofitted so that the limit values for the emission of NOx specified for the
vehicle in column (f) would not be exceeded during the appropriate test or tests specified in
column (g) of the Table; or
(c) in respect of all other vehicles, the Central Clean Air Zone Service is satisfied that the limit values
for the emission of NOx specified for the vehicle in column (f) would not be exceeded during the
appropriate test or tests specified in column (g) of the Table.

It surely passes under (c). The VCA state the NOx level on their database and it is well under 80mg. Surely this should satisfy that the limit would not be breached if a "Type I" test (whatever that is) were undertaken.

I assume the NOx is not listed on the V5c, but a print out of the appropriate VCA page for the exact variant

https://carfueldata.vehicle-certification-agency.gov.uk/search-new-or-used-cars.aspx

Showing Euro 3 and NOx specified as approx 34mg may help in an appeal.

Being Birmingham and no discount reoffered they may well simply be "computer says no" but personally I think I would much rather pay full fines at tribunal rather than half price.

I have requested a certificate of conformity from Porsche (free service hooray!) so this should hopefully clear up the Euro status and NOx emissions. However they said this could take up to 28 days to arrive so in the meantime I guess I should still make representations and state that this certificate is on the way?

Yes, representations must be made by day 28 at the very latests or else you've lost.

So to update and close out this thread: Birmingham city council rejected my representations (no surprise really) so I appealed to the traffic penalty tribunal and they cleared all my PCNs, hooray!

For anyone in a similar predicament, the process was:
- Obtain a certificate of conformity from the manufacturer (took 4 weeks)
- Send in a copy of the CoC along with the V5C to the DVLA so they could update the emissions details (took 4 weeks)
- Fill in a form on the CAZ website and upload a scan of the V5C (updated instantly!)

Thanks for everyone's help and input, there were actually 4 PCNs in the end which would have added up to a painful amount!
And lesson learned - never assume government databases are consistent with each other. Just because a car is ULEZ compliant does not mean it's CAZ compliant and vice versa.

Well done!

Please post up the decision, as TPT decisions are not online, and it may help others.

Well done!

Please post up the decision, as TPT decisions are not online, and it may help others.

They basically just said the authority did not contest as my vehicle is now showing up as compliant on the checker.