On the right side, they speakin terms of how many liters it takes to go 100 km.

Of, no they don't! At least, only in the mainland. Britains still measue distances in miles, and judge the relative efficiency or otherwise of ICE-powered engines in terms of "m.p.g." (miles per gallon)
Electric powered vehicles are measured in terms of "miles per charge" - i.e., the distance you can go before you have to hook up t the mains electric to re-charge the battery.

Now - I wonder how fiberbabe meaures the economy of her little econo-wonder? ( I suppose it must be m.p.g., as she doesn't have to hook up to the mains at any time?)