If your current fire extinguisher is powder-based, and the product information shows that it is clearly suitable for use on electrical fires, then it makes sense to keep this in your new car. However, it is important to note that this would likely only be of use in attempting to extinguish a fire in the car's general electrical system and it would not be suitable for attempting to extinguish a fire in the vehicle's main drive battery. A company recommended by the UK Fire Service said that the most effective method was to use a fire blanket designed for vehicles, but unfortunately these are quite expensive and are not designed for public use.