I'm not doing stuff like that but I assume the train of thought concerning the economics of energy consumption is like that: You buy new hardware and from experience you know it's going to last on average a few years. During the lifetime of your new hardware you can save some amount of money on electricity because your new hardware is more efficient than the old one. So it would make sense to hit the buy button for the new hardware when you can save money:
(Savings in electricity over the lifetime) - (Price of new hardware) > 0
I assume after a few years the savings may become significant.
Big tech companies are often running hardware for longer than you think - just not using old hw for cloud hosting.
For cars it is much more important to calculate the risk of it failing in some moment you need it, and the costs of being suddenly carless. Also, for cars that go on a road, the most relevant factor is safety.