Battery wise there a bit like the relationship between the amount of fuel you burn and the amount of CO2 you get out of it, in essence the amount of power you can get from a battery, and the amount of power you want the motor to be capable of, decides the range.
Yes you can make a car lighter or more aerodynamic to reduce losses, but the amount of impact that will have is fairly minimal, if the care is already reasonably aerodynamic.
Then there is the weight, these days everyone wants their gadgets so they can't take too much away.
I dare say if you took the running gear from something like an i.D3 and then fitted it to something that didn't have all the fancy heated everything electric windows all round, didn't have 4 usb charging sockets for everyones phones , maybe used lighter weight plastics, what you'd have is a better range but a car people would not buy because of it looking or feeling "cheap"
So really to get people to switch over they will have to make cars that look and feel exactly like cars do now, and just substitute the engine for a motor.