It is so sad when an icon is found to be wanting.
But I can confirm your observation that MMC has overstated their data. This has serious financial consequences in the UK where annual car tax is based on CO2 emissions. I pay £505 per year based on the CO2 output of 282g/km.
Based on your evidence, which I can largely confirm, the figures are overstated by 15%. Reducing the CO2 emissions by 15% would cut my annual tax by £!5.00!!!!
I find this rather odd, as all the newer Morgans as I understand it are fitted with engines, ECU etc supplied by 3rd party manufacturers (BMW and Ford) so as these units are supposedly locked down then do not the Emission figures submitted by the 3rd parties for these engines apply with the authorities. Obviously if a limited run and a tuned variant then Emissions would need to be specified by MMC. Or am I misunderstanding something here?