Remember, when you charge your cell phone, you charge at ~15W (or less), so 80% efficiency is something like 3W of power loss. You can dissipate that pretty eas

Remember, when you charge your cell phone, you charge at ~15W (or less), so 80% efficiency is something like 3W of power loss. You can dissipate that pretty easily. For a car charging, you're charging closer to 7-11kW. Dissipating 2.2kW (20% of 11kW) as heat is basically impossible. The inductive charging they're using for cars (which, are basically mostly prototypes at this point) are different and use much more closely coupled coils... so they can get better efficiency. Whether it works in practice, I don't know, but that's what companies are claiming who come out with these solutions.