If not charged correctly, i.e. with a charger not specifically designed for Lithium, they can burst into flames and have been known to do so during charging. They are used quite extensively in electric planes but have limitations as to discharge rate so you need to make sure you have a "pack" that can discharge at a great enough rate for your car. You simply order packs that have enough cells wired in series to provide you with the voltage you need, 3.7V/cell. Your speed controller should be able to handle it (assuming the pack provides a voltage in the proper range) as it regulates voltage, it doesn't really know what kind of battery it's connected to. Check out the car forum, I'm sure there are a lot of helpful people there that can give you specific information for your car.