Gas Prices
When I was a teenager, I played a paper-and-pencil game called Car Wars with a group of similarly geeky friends. In this game you designed armed and armored vehicles and played them against one another or in missions.
The game was set in the far future (2040s, maybe?), and one of the things that constantly reminded you of this was that most cars were powered by electric motors. Gasoline engines were available, and they gave superior performance, but gas prices were ludicrously high, a tactic which usually worked to discourage their use.
That “ludicrously high” price? Five dollars a gallon.
Looking at today’s gas prices, I suspect that five dollars a gallon by 2040 was… optimistic.