From Fairphone: The most sustainable phone is the one you already own. In part:

A phone’s biggest environmental impact comes from the manufacturing process. That’s why – whether it’s a Fairphone or something else – the most sustainable phone available is the one you already own. So the longer you keep it, the more sustainable it becomes. Extending the lifespan of existing phones is the best strategy for reducing their impact on the planet. And it’s not only good for the earth – it’s easy on your wallet, too!

While keeping our 2000 Volkswagen Jetta has been mostly due to frugality and limited resources, I do take some pride in having not needed to cause another car to be created to replace ours.