Electric powered vehicles and Hybrids! The core concept of this is pretty simple, add vehicles that are powered by electric motors (or whatever the 2106 equivilent is) and have two different types of components for electric vehicles.
Power Cell: Holds/Stores electricity. There could be different types of this, hybrid versions, self recharging. Let's just get down to a little detail with these.
Self-Recharging Power Cell, uses solar power, slow time to re-charge, doesn't hold much. You could perhaps use it in your day to day mall trips on small economical vehicles.
A normal Power Cell, this could come in three sizes, Small, Medium, Large. Pretty self explanitory, they're not self recharging, and requires a charge station to charge them.
Hybrid Power Cell, now this one I like the idea of, it uses the power/fuel of an engine that's running for a vehicle to charge the Cell, so the engine can turn off and switch to electric power while driving.
Drive Motor: This is pretty simple so I won't go too much in to detail, but this would be on purely electric vehicles. You could also hve different types of this, this one is basically the 'engine' of the vehicle, and dictates how fast you go, and how much electricity you'd use while driving. You could even have Hybrid Variants that you can stick in to normal cars and have them be powered by electricity too.
This is just an idea, and honestly I have no idea how difficult this would be to impliment, however this does seems like it would be something pretty amazing vehicle wise to add, and would add to the flavor of types of vehicles.