UKC

I am currently climbing in Spain and I hired a 1.25 petrol Ford Fiesta. I am getting 33mpg with mixed driving. At home I have a Skoda Octavia 1.6 TDI, and similar driving gives me 52 mpg. The Co2 emission figures for each car is almost identical, the Skoda infact is slightly better. The Co2 emissions are measured in gms/ litre. The fact that the mpg of the Skoda is far better than the Fiesta should surly that be taken into account in comparisons as it uses far less fuel. I realise that nox emissions are also a problem but it is Co2 that is causing climate change. In regard to nox emissions modern diesel are not that bad.

Emissions are given in g/km rather than g/litre for the purposes of VED. So the efficiency is taken into account.

Are you taking in to account the well known fact that nothing handles quite like a hire car?

Except diesel burns to produce more CO2 than petrol.

My mistake

NOx is also a greenhouse gas, contributing to climate change.

I wouldn’t pay too much attention to the dashboard stats on fuel consumption for comparison between two cars made by different manufacturers...

It's well known that diesel is better for CO2 emissions, which is why we had a push to them a decade ago.

But they are much worse than petrol for NOx and particulates. In real world conditions even the most modern diesels are failing required standards.