Would you buy an used (3 yr old) diesel car now?

[wax lyrical]

I'm thinking about a Mercedes GLB diesel (2020 car) using a 4 yr loan (plus initial deposit) - so owning the car outright at the end of the 4 years.

Given the way the UK is moving (electric cars, ULEZ, etc) is that a silly idea? I assume the market for 7 year old diesels in a few years time will be almost non-existent?

All input and advice appreciated!

[wax lyrical]

Thanks Guys.