That's just nonsense, you can't.

Feel free to add a source that is transparent about all non-fuel costs.

There's tons of false advertising, e.g. rent a car for 1 euro a day (service charge), but also pay a maintenance charge, an insurance charge, a monthly membership fee etc etc.

For example I have a 3 euro a day rental, but I also pay monthly.

Typically cars will cost about 30-35 euros or so per day, for the cheapest ones, with possibilities here and there to do 15-20 in certain seasons under limited conditions.

I have a time believing that figure... Where did you get it from?

I can't confirm OPs number but I have in the past hired a car for less than 6 euro a day in Ireland.

The problem is these prices are trap. I think its a big risk since the car is not covered - if anything happens to it (somebody crashes into you or even malfunction) then you pay for it.

Not without a license.