I don't have the links that you are looking for, but from an engineering standpoint it makes total sense that an EV would have lower maintenance, and at least eventually, much higher reliability.
There are far fewer moving parts and wear items in an EV than in a ICE vehicle. Going off a WAG there must be 1/10 the number of moving parts compared to a vehicle with 4,6,8 cylinders, transmission, exhaust system, cooling etc. Furthermore none of those are exposed to exhaust gases, combustion byproducts, or under go near the thermal stresses in a combustion engine. There is far less heat to get rid of as the motors are far more efficient, and the brakes are rarely used, so heat and wear there is also much lower.
In some ways the engineering in EVs is not as mature as ICE vehicles that have been continuously under development for decades, so the absolute reliability numbers may not be there yet, but they surely will be better in time. The body and chassis are not much different, and electric motors are extremely mature tech, it is more a matter of integration.