The main benefit is efficiency and zero harmless emmissions.
They’re more efficient because of the process of using electric motors instead of burning fuel. This means the theortical efficiency of an electric car is somewhere in the region on 90%. Whereas fuel vehicles are limited by the laws of thermodynamics and can only ever achieve something like a 40% efficiency (By efficiency here, I mean how much torque is generated for a given amount of energy put in).
If the car generates zero emmissions then there are benefits to the local air quality. Clearly if the electricity generated is from a coal burning power station down the road… then this isn’t much use. However, when you power electric cars electricity generated by renewable energy sources, we have the golden formula!