Actually, if you read a bit
Actually, if you read a bit more about the RAV4 hybrid, you'll find out that the vehicle can go on the battery only for a short mileage: "In reality, the Toyota wasn't designed to make long battery-powered trips. Instead, the RAV4's electric motor is intended to keep you mobile at times when running the petrol engine would be wasteful, such as when inching forwards in stop-start traffic, or manoeuvering at low speeds at the beginning and end of your journey."
So there isn't big advantage, over the petrol version, yet you'll have one additional power source to worry about. Because the hybrid battery does get hot, and because of this, it has it's own cooling system ( which often fails). You can read all this in Toyota hybrid forums.