It is easier and cheaper to keep 100 litres of gasoline for emergency which would allow to drive at least 1000 KM.
> CPSC also warns consumers that private storage of more than a limited amount of gasoline (usually five gallons or less) is illegal in many areas, and subsequent fire damage may not be covered by insurance policies.
More recent advice from the API indicates that fire codes usually restrict the storage of more than 25 gallons (~95 L) at home. Many people in rural areas would have orders of magnitude more than that.
So it seems that, in the US at least, it's not illegal all over.
API Source: https://www.api.org/oil-and-natural-gas/consumer-information...
These tanks are outside, though they could start the building near them on fire if something happened.
https://www.hse.gov.uk/fireandexplosion/petrol-storage-club-...
Also it goes off after like 6 months if you are not using it.
https://www.rac.co.uk/drive/advice/know-how/does-fuel-go-off....
Even above 275L, it says you need a license - it doesn't say it's illegal.
Fuel does go off, but if you have reason to store it, you probably have a use for it, so as long as you cycle the fuel, you can store an emergency supply indefinitely.
Its commonly said 'it illegal to possess plutonium', but obviously someone does operate nuclear powerplants, and thise are people with the right licence. Same applies to drugs, explosices, etc.
The question is - are requirements of the lisence realistic for you to meet as an average homeowner?
However, I picked a random Council to see, and it looks extremely doable for a homeowner with the space to do so to get a license to store up to 2,500L. It's not even particularly expensive (£44 pa)
http://www.suffolk.gov.uk/community-and-safety/suffolk-tradi...