The size of the battery determines the range. Currently, batteries of 30 - 80 KW are installed in the cars on offer.

These batteries are heavy and take up a lot of space. They are usually installed under the passenger cell. In conventional "burners" this energy storage is hardly worth mentioning and is limited to a container of about ~30 Kg, near the spare wheel.

Why do I need so much space and weight for the energy to drive in the e-car and so little in the combustion car?

One Kg of diesel/gasoline corresponds to an amount of energy of about 10KW.
An E-car battery, charged with 40KW energy, thus corresponds to about 4 Kg diesel/gasoline!

So, in order to "refuel" an e-car with the same amount of energy that a known "combustion engine" can refuel (about 30 Kg of fuel), a battery weighing 2250 Kg with an energy of 300 kw would have to be installed.