Here are some figures on CO2 output for domestic vehicle travel in the UK https://www.gov.uk/government/statistics/transport-and-environment-statistics-2022/transport-and-environment-statistics-2022

( unfortunately for 2020, during lockdown - so add 20%ish to get 2019 )

domestic transport was responsible for emitting 99 MtCO2e (million tonnes of carbon dioxide equivalent), a 19% reduction from 2019 and the largest fall in emissions on record.

So, if you’re right and 8million is about a quarter of the cars, that’s about 25m tonnes of CO2)

OK very tough calcalculation stupid assumptions, but just sanity checking.

• Assuming 60million people in the UK

• Assume all are heavy meat eaters (no)

• Assume they cut down saving 5kg of CO2 a day, I make that

108Mt a year saved.

So actually, it would take a quarter of the population being heavy meat eaters cuttting down to get to the 80m cars.

So - not entirely mad?

Note - my maths is really really bad, so I could well have made egregious errors here