Whoa guys, serious misunderstanding here (could be me). I understand 240v is faster, I just don't understand why you need an outboard charger. You are still going through the same plug on the car, going through the same inboard charger. Why not simply connect 240v directly to an outlet? Why the need for an expensive outboard management unit? You will still be limited to the onboard charger maximum speed, right?
The "charger" that comes with the car isn't really the charger. It is what's called Electric Vehicle Service Equipment (EVSE). And yes, it's necessary to communicate with the car to ensure proper charging. The charger itself is contained in the car, and is a fixed size. In the US, the car comes with a Level 1 110vac 12 amp EVSE. Johnxyz outlines very well what it is capable of providing. With a Level 2 EVSE, you have the ability to charge the car with 220vac at 16 amps. So it's significantly faster at charging the battery.
One thing to note is that a larger EVSE, such as a 32 or 40 amp unit, will not charge our cars any faster than a 16 amp unit. Our car's on-board charger accepts 16 amps maximum, so a faster EVSE does nothing. But it might offer features such as WiFi connectivity that you might like. It won't hurt our cars to use a larger EVSE, but there's no benefit to charging it either.
Remember that many other countries have 220vac as their "standard" home power, while we in North America have 110vac. So in those countries their "standard" charging is faster than ours. Although I will admit I don't know what amperage a typical home outlet has in the places with 220vac. Most US homes have a 15 amp circuit on most outlets, and that is typically shared with multiple outlets. When we have a 220vac outlet available, it's typically dedicated to a single outlet, although its current capability can vary from 20 to 50 amps or more, depending on the size wiring.