The electric motor has been around nearly two centuries, but it was largely abandoned for use in cars until this century. Its recently sustained emergence in the personal vehicle market is spurring innovation needed for it to replace combustion engines on a large scale.
There is no one, agreed-upon motor design, and auto manufacturers are busy developing technologies to give their models the leg up on their competitors. The combustion engine, on the other hand, is settled technology with refinements along the way to boost either power or fuel economy, for instance.