Hello there,
Sorry, I was intending to post my result and forgot all about it.
My 2000 Scudo Combi was registered with the DVLA as a van with side windows so was not compliant with the lez. I got a reply from a very helpful person at Fiat and I will send you his contact details if you contact me. I sent him an email with a copy of the v5, photos of the vin plate, pictures of the inside with the seats in and an explanation of my problems.
He replied almost immediately with a letter for TFL and one for DVLA explaining that the vehicle was an MPV and the registration class it should be in etc. I sent this to TFL (who have been very helpful when I phoned them) and they sent me a letter back about 3 days later classing my car as not subject to the LEZ, meaning that I can use it in London. Great result. Everyone was really helpful.
I will happily send you more information if you wish but it would be better to email everything.
Contact me and I will send you everything I sent and received.
The person at TFL did say that although they had classed it as not subject to LEZ, unless I got the car reclassified at DVLA, after about 3 months, their database would be updated from DVLA with the incorrect information and the car would revert to being non-compliant.
By the way I am not sure how the earlier person got their van classed as euro3 as the 2000 model is definitely only euro2 so could not be compliant as a van.
It is worth noting that the later vehicles with the 16 valve engines have worse fuel consumption and qualify for £400 pa road tax.
Good luck,
Richard.