There's a neat feature in the BMW X5 xDrive45e (a petrol plug-in hybrid SUV) - when you enter a low emissions zone, it automatically switches to battery power.

Moving emissions away from the tailpipe in heavily populated areas seems like a great idea.

There's no free lunch though. The emissions are still happening, just in different places where they're, ideally, less likely to affect people.

It's a better situation but it's not yet perfect.